Category: Study Materials
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Photoautotroph: Definition, Types, & Function
Continue ReadingPhotoautotroph Definition
The organisms that can make their energy in presence of light and carbon dioxide are known as photoautotrophs. The process of preparing their own food is called photosynthesis. The word photoautotroph is made by two words, photo + autotroph.
The word photo means light and the autotroph word is used for the organisms that make their own food. Examples of photoautotrophs are green plants and photosynthetic bacteria. However, they are different from photoheterotrophs, which also make energy in presence of light but do not use carbon dioxide and instead use organic materials.
Photoautotroph Function
Photoautotrophs can reproduce and survive because they make their own food. However, heterotrophs also require food for survival but they obtain nutrients and energy from other organisms.
Heterotrophs consume autotrophs such as plants provide food for cattle and then humans consume the cattle. In the food chain, the autotrophs remain at the bottom and provide food for other organisms.
In any ecosystem, photoautotrophs have a significant role. Since the nutrients required by organisms to survive are produced by plants, thus they are also called producers of the food chain. Humans and other animals would not survive without the existence of plants because they would not have food.
Another important role of photoautotrophs is they fix atmospheric carbon dioxide, which is a byproduct of respiration in heterotrophs. In addition, they also give off oxygen as a result of photosynthesis, which is used by all heterotrophs and is vital for their survival.
Types of Photoautotroph
i. Green Plants
All the green plants are photoautotrophs, however, there are some exceptions such as the Indian Pipe. In this category, all the plants including grasses, mosses, and trees are included. In terrestrial ecosystems, plants are the major source of food.
They contain a photosynthetic pigment, chlorophyll in organelles named chloroplasts within their cells. Thus they can make their own energy by using light and carbon dioxide. The light is absorbed by the chlorophyll and light energy is transferred into parts of the plants.
The green color of leaves is also due to chlorophyll. Indian Pipe cannot produce chlorophyll, thus it cannot produce its own energy from light, and to obtain nutrients, it lives as a parasite in certain species of trees.
ii. Bacteria
Some photosynthetic bacteria are also able to make their food such as cyanobacteria or blue-green algae. Cyanobacteria also produce chlorophyll. In fact, it is also thought that plants were originated from blue-green algae.
Millions of years ago, cells engulf cyanobacteria where these bacteria make food for those cells and in return get a place to live. This means that the chloroplasts in plant cells are actually cyanobacteria.
The chloroplasts are copies of the cyanobacteria that reproduce asexually. Other photosynthetic bacteria are green sulfur bacteria, which is ecologically similar to cyanobacteria but instead of water, it uses sulfide ions during photosynthesis.
iii. Algae
There are many forms of algae, such as single-celled or multicellular algae. In aquatic ecosystems, algae are the major producers however they are absent in terrestrial ecosystems.
All algal species are thought to derive from different ancestors thus only some species perform photosynthesis. Algae also produce a large proportion of oxygen even half of the total atmospheric oxygen is produced by algae. Sometimes algae also disrupt the ecosystem if it flourishes too much.
Algae produce certain toxins and make nutrients less available for other aquatic organisms. Often human activities are also responsible for algal blooms. The use of nitrogen-containing fertilizers and improper treatment of wastewater are some major causes.
However, algae also fix atmospheric carbon dioxide and in the future, it may be able to use as a source of biofuel in place of fossil fuels.
Photoautotroph vs Chemoautotrophs
Another type of autotroph is chemoautotrophs. They are also able to make their own food like photoautotrophs but instead of light energy, they use chemical energy. Thus, they can easily survive in light deficient conditions or absence of sunlight, such as the deep ocean floor. Nitrogen-fixing bacteria and iron-oxidizing bacteria are some examples of chemoautotrophs.
Photoautotroph Citations
- Impacts of Micro- and Nanoplastics on Photosynthesis Activities of Photoautotrophs: A Mini-Review. Front Microbiol . 2021 Nov 17;12:773226.
- A review on the progress, challenges and prospects in commercializing microalgal fucoxanthin. Biotechnol Adv . 2021 Dec;53:107865.
- Photosynthetic adaptation to polar life: Energy balance, photoprotection and genetic redundancy. J Plant Physiol . 2022 Jan;268:153557.
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Microtubule: Definition, Structure, & Function
Continue ReadingMicrotubule Definition
Microtubules are a part of a cell’s cytoskeleton. They are hollow tubes made of the proteins alpha and beta tubulins. Microtubulin form a network of protein filaments extended throughout the cell that gives the cell shape.
Microtubules are thicket among all the structures in the cytoskeleton, their thickness is about 24 nanometers. The microtubules helps in cell division cell movement and in transportation of materials within cells.
Microtubule Structure
The structure of microtubule is made of dimers of alpha and beta tubulin. They form hollow cylinders of repeating protein structures. The proteins α-tubulin and β-tubulin bind to each other and form complexes of dimers.
They always bind in alternating manner and form a chain known as protofilament. A microtubule is formed by thirteen protofilaments that arrange into a cylindrical pattern. The dimers constantly add and remove and thus microtubules constantly assemble and disassemble.
Their state is maintained even though the individual molecules themselves are constantly changing thus they are said to be in a state of dynamic equilibrium.
Microtubules have positive and negative charges ends the positive charged end grows relatively fast than the negatively charged end. The arrangement of protofilaments is parallel to each other, so the beta subunits are always exposed in the positive end of the microtubule, while the alpha subunits are always exposed in the negative end.
The microtubules assembles in a specific way and do correct function due to its polarity. Microtubules radiate outwards from an organelle called centrosome in animal cells. Centrosome is located in the center of the cell and called microtubule organizing center (MTOC). Centrosomes are not found in plants and fungi and MTOC surrounds the cell nucleus instead of nuclear membrane.
Microtubule Functions
i. Cell Movement
The structure like cilia and flagella are formed by microtubules. A small protuberances of a cell is called cilia. In humans, the linings of trachea consist cilia that prevent materials like mucus and dirt from entering the lungs.
The fallopian tubes of females also have cilia that helps in the movement of egg released from the ovary to the uterus. Another tail like appendages are called flagella that also helps in movement.
Several bacteria and human sperms contain flagella which allows them to move. With the help of microtubules, whole cell can crawl or migrate from one place to another by contracting at one end and expanding at another.
ii. Cell Division
The other important function of microtubule is in the formation of mitotic spindle, which is also known as spindle apparatus. During mitosis, the structure is formed in eukaryotic cells which helps in separation of chromosomes equally during cell division.
It organizes the chromosomes so that they can be partitioned into separate daughter cells. Microtubules MTOCs, and microtubule-associated proteins are the components of spindle apparatus.
Microtubules are categorized in three subgroups- astral, polar, and kinetochore microtubules that aid in process of mitosis. Astral microtubules radiates from the MTOCs of the cell and it keeps the mitotic spindle in place.
The chromosomes are separated by the polar microtubules that also interwine between two MTOCs. The chromosomes are pulled apart towards opposite poles by the kinetochore microtubules. The kinetochore is a complex of proteins attached to the microtubule.
iii. Cell Transport
Microtubule is a part of cytoskeleton, thus it also play role in movement of organelles inside a cell’s cytoplasm. It include all of the cell’s contents except for its nucleus. Various areas of cell can communicate with each other with the help of microtubule and it also provide shape and structure to the cell.
Other Cytoskeletal Components
The eukaryotic cytoskeleton is made of microtubule along with microfilaments and intermediate filaments. The diameter of microfilaments is about 7nm, which is smaller than microtubules.
They also have various vital functions in the cell such as cytokinesis, role in cytoplasmic streaming (flow of cytoplasm) throughout the cell. Intermediate filaments provide the shape and structural support to the cell and they are larger than microfilaments but smaller than microtubules.
Microtubule Citations
- Nine-fold symmetry of centriole: The joint efforts of its core proteins. Bioessays . 2022 Jan 7;e2100262.
- Structural and Functional Insights into the Microtubule Organizing Centers of Toxoplasma gondii and Plasmodium spp. Microorganisms . 2021 Dec 3;9(12):2503.
- Microtubule-Interfering Drugs: Current and Future Roles in Epithelial Ovarian Cancer Treatment. Cancers (Basel) . 2021 Dec 12;13(24):6239.
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Chukar: Description, Habitat, & Fun Facts
Continue ReadingChukar Classification
Kingdom– Animalia
Phylum– Chordata
Class– Aves
Order– Galliformes
Family– Phasianida
Genus– Alectoris
Species– Alectoris chukar
Chukar Description
The chukar (Alectoris chukar) belongs to the family Phasianidae. It is an upland gaming bird. At first, chukar was considered a species of partridge as rock partridge, Philpy’s partridge, and Przevalski’s partridge.
They are mainly distributed to Asia but are now also found in parts of North America and New Zealand.
Chukar consists round body with small wings and feathers with black and white marks. The body appears light brown to grey that may change between populations. A solid black band forms a necklace-shaped ring and represents the face of the chukar and the breast have a white section.
A red outline covers their black eyes, which also matches their red beak. The legs are also red with clawed toes. A spur is present in the legs of males, which is absent in females. Females are also shorter than males.
The choker can be found throughout Asia including the western Himalayas to Nepal and also occur in northern Africa on the Sinai Peninsula. They prefer their habitats in rocky, grassy, and open hillsides in scrublands.
They usually reside in higher altitudes but in some areas, they are also found in low altitude areas. It is a common game bird of hunters for this they are now introduced to New Zealand, Hawaii, and mainland North America and to other parts of the world. They are non-migratory birds.
Chukar Predators and Threats
Chukar usually lives in small groups of around 10 birds. They prefer grassy lands and low-lying mountains for their habitats. The predatory organisms especially mammals feed on the chukar. For example, they are hunted by coyotes and bobcats in North America.
They can be easily targeted thus sometimes hunted by owls, hawks, eagles, and other larger birds. Chukars can fly but their body shape, short wings make it difficult and keep them on the ground. They prefer to run when disturbed.
The distribution of these birds around the world is also done for hunting and they have long been hunted by humans also. People use various unique techniques such as they force the bird to fly longer than its ability and tire it, at last chukar allow them to catch them.
But unlike many other species, chukar is not facing any habitat loss due to human development. However, the weather patterns affecting the populations especially during their breeding season.
Global climate change also has some impacts on local weather patterns. Seasonal events are also affecting by climate change that increases extreme weather events such as storms. These events have also an impact on chukar populations.
The food of chukar is primarily made of seeds but they are omnivores thus also eat insects. In arid parts, to avoid scarcity of water, they also eat succulents.
Chukar Nesting and Reproduction
They pair up with their mates in the breeding season. Males perform various display activities such as pecking at food to impress the female and female joins male if impressed. Males then catch females with their dropped wings, ruffled feathers, and low heads.
During this time, males or cocks often become aggressive to find a mate that often results in conflicts. After pair up, males remain monogamous and only mate with a particular female for at least during that breeding season.
The copulation is followed by nest formation, which is done by female chukar. She use grass and other soft materials and made a small depression in the ground to make a nest.
The female lays 7-14 eggs at a time, which are incubated for 3-4 weeks before hatching. Chicks form a convoy with other females until the next breeding season.
Fun Facts About Chukar!
i. Spelled just like it sounds
Chur sings a noisy song chuck-chuck-chukar-chukar therefore it gets its name chukar. They make this sound, especially in the mornings and evenings. A ‘rally’ call is one of their calls they used to bring the group together to protect them from a predator or any other threat such as storms. They also named Keklik and chukker in some parts of the world.
ii. The Evolution of Flight
Young chicks of chukar cannot fly until they learn a technique called “wing-assisted incline running”. The technique is considered as a model to explain the evolution of flight in avians. The technique is also present in many other bird species.
In wing-assisted incline running, the bird moves upslope while flapping their wing that helps them move up slopes easier than without the aid of their wings. This technique is seen in young birds of many species before learning to fly.
iii. Not like the others
In the past, chukar species were considered members of partridge species such as rock partridge (Alectoris graeca). But the phenotype of chukar partridge is different from the rock partridge, it has a browner back and more yellowish throat section than the rock partridge.
The red-legged partridge has a similar appearance as chukar. The Barbary partridge (Alectoris Barbara) consists reddish-brown collar and a grey throat and face that can be easily distinguished by the black collar of the chukar.
The chukar species are also distinguished based on their ranges. For example, the area of the Middle East and Asia is occupied by chukar which is replaced by the red-legged partridge species in southeastern Europe.
The chukar and partridge species also interbreed on getting the opportunity and also show various physical similarities but eventually, they are separated as different species.
They may share a common ancestor and undergo speciation due to their geographical divisions. The hybridization of captive stocks of these species is a threat to wild populations thus it is banned in many parts of the world.
Chukar Citations
Sperm characteristics of Chukar partridge (Alectoris chukar) breeders as affected by the addition of calcitriol to the semen extender. Poult Sci . 2019 Aug 1;98(8):3292-3297.
Parasitosis of the chukar partridge, Alectoris chukar in North Iraq. Turkiye Parazitol Derg . 2012;36(4):240-6.
Effect of sex ratio, storage time and temperature on hatching rate, fertility and embryonic mortality in Chukar partridge (Alectoris chukar). Anim Reprod Sci . 2019 Apr;203:68-74.
Phylogeography of chukar partridge (Alectoris chukar) in China based on mtDNA control region. Mitochondrial DNA A DNA Mapp Seq Anal . 2017 Jul;28(4):473-481.
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Swan: Description, Habitat, & Fun Facts
Continue ReadingSwan Classification
Kingdom: Animalia
Phylum: Chordata
Order: Anseriformes
Family: Anatidae
Subfamily: Anserinae
Genus: Cygnus
Species: 6 species
Swan Description
The swan is a genus of the family Anatidae consisting of 6 species. They are distributed in the temperate regions of the world including North Americ, Eurasia, Australia, and Southern America. They belong to the waterfowl family with ducks and geese.
Of all 6 species, four have purely white plumage that is found in the Northern Hemisphere, and the other two species found in the Southern Hemisphere including black swans and the black-necked swans.
Swans feed mainly on the leaves and stems of submerged vegetation of water bodies, thus they are pure vegetarians. They usually dip their head or upending their whole body to feed in the water.
They also eat the roots and tubers and obtain them by digging into the substrate. However, at the juvenile stage, the swans are not vegetarian and feed on insects and crustaceans to increase their protein intake, but they adopt herbivory in their maturity.
Swan Reproduction
The shallow ponds, undisturbed lakes, slow rivers, wetlands, are preferred breeding habitats for swans. Due to their large size and weight, they require large water bodies or open lands for taking off.
They make their nests on mounds of aquatic vegetation close to the water’s edge. The nest is normally made by both parents that are used for several years after repair. Swans are monogamous, and both take care of eggs. Typically 3-8 eggs are laid by female swans, the number can increase up to 12 eggs in some species.
The trumpeter swan is the largest swan, which lays the largest egg among all flying birds. The egg weighs up to 11.3 ounces and has 2.9 inches in width, 4.5 inches in length.
In some species, both the parents incubate the eggs for 3-45 days, whereas in some other species females incubate, and the male guards the nest. Most of the species of swan show territorial behavior only during the breeding season and protect their nests from predators, and other animals.
However, some species are territorial year-round. After hatching the eggs, the cygnets become able to swim after few days. However, they complete long distances on their parents’ backs.
The swans show parental care for their young for 3-5 months in most species. However, the cygnets can feed on their own after few weeks. The black swan shows much longer parental care and cares for around 9 months.
The juveniles of tundra swans develop faster as compared to other swan species and are thought to fledge after 40-45 days.
Fun Facts About Swan!
Besides their beautiful appearance, swans also exhibit several interesting adaptations.
Migration Swan
Swans use separate summer and winter ranges thus called partially migratory species. The long-distance movement of organisms on a seasonal basis is known as migration. Bids, mammals, reptiles, amphibians, fish, insects, and crustaceans all involve migratory movements.
The migration is affected by several factors such as local climate, mating requirements, season, food availability, etc. individuals migrate to complete their needs. For example, humpback whales migrate in winter to the warm waters of the pacific to give birth in the warm waters.
Swan including whooper swan and tundra swan are fully migratory species. They breed at northern latitudes during summer and then migrate towards southern latitudes.
The mute swans have the resident populations that exist in Western Europe, they are the only partially migratory swan species.
The black swan shows erratic migratory patterns thus it is called nomadic. They mainly migrates based on rainfall and climatic conditions.
Brittle Bones
The largest flying birds in the world include swans. The trumpeter swan, found in North America is considered the heaviest extant bird. To fly successfully, they need all the possible help including their weaker bone structure.
The bones are distinguishable by bones of other animals, which are honey-comb-like structures. The bones of swans are more vulnerable to breakages.
The weaker bones are an example of a trade-off. In this phenomenon, a beneficial change of one trait is connected to a harmful change in another trait.
For example, the body size, bone density, and flying ability of a bird cannot be optimized simultaneously due to the laws of physics. This problem is overcome by different species in different ways such as hummingbirds reduce their size, and swans evolve weak bones.
Mutual Courtship
Swans are monogamous and before reaching sexual maturity, they form pair bonds. For example, the trumpeter swan forms pairs from as early as 20 months old but it reaches sexual maturity at the age of 4-7 years.
Like other socially monogamous bird species, swans also follow courtship rituals before mating that strengthen their pair bonds. The courtship rituals in swans may vary.
It includes the formation of heart shape with both of their necks of male and female. They also use vocals during these rituals and black swans use specific feathers in their courtship ritual. The vocals also vary among species.
For example, a honking sound is produced by trumpeter swan with head bobbing, and soft sounds are produced by tundra swans and whooper swans after mating.
Swan Citations
- Treating the Proximal Interphalangeal Joint in Swan Neck and Boutonniere Deformities. Hand Clin . 2018 May;34(2):167-176.
- Volar transfer of the lateral band with transverse retinacular ligament is effective for the correction of swan-neck deformity caused by volar plate injury of the PIP joint. Mod Rheumatol Case Rep . 2020 Jan;4(1):152-155.
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Secretary Bird: Description, Habitat, & Fun Facts
Continue ReadingSecretary Bird Classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Accipitriformes
Family: Sagittariidae
Genus: Sagittarius
Species: Sagittarius serpentarius
Secretary Bird Description
It is a type of terrestrial bird, which has native distribution among grasslands and savannahs of sub-Saharan Africa. The species belong to the family Sagittariidae, which consists of only living species.
They have long legs that look like cranes and the body and head resemble eagles. Their long legs extend their height to 4.9 feet.
They are found in grasslands where the length of the grass is less than 1.8 feet and avoid areas with long grasses of more than 3.3 feet.
There are two species of terrestrial birds of prey including secretory birds and caracaras. Caracaras are found in the regions of Central and South America. Their long legs help them to lift their body above the vegetation to spot the prey easily to hunt them.
They are terrestrial birds that mean they hunt on foot. They mainly feed on smaller mammals, amphibians, reptiles, birds, and insects. Sometimes they also act as scavengers and feed on dead organisms.
They hunt and police their territories and spend most of their time in these activities. These birds tend to hunt in proximity to their breeding partners or also in small family groups.
During the hottest part of the day, they take a break and rest in the shade of the tree but otherwise they hunt throughout the day. They cover long distances of more than 20 miles per day to hunt their prey.
Secretary Bird Reproduction
Secretory birds mate only with a single partner that means they are monogamous. They also make their territories that are much larger up to 19 square miles in size. They usually breed throughout the year however it is common in the late dry season.
A nuptial display is performed by both males and females which is done by making a loud croaking sound and soaring high above the ground.
They defend their territories by chasing each other with their wings up and back. They make their nest together and place it at the thorny acacia tree.
It takes around six months to build their nest with the help of twigs, leaves, grasses, animal fur, and dung. The nest is placed between 8-40 feet over the ground and has up to 8 feet width. The same nest of often used for several years.
The eggs are pale blue-green or white. Female lay 1-3 eggs at 2-3 days intervals. Most of the time, females are on the nest but eggs are incubated by both parents. After 45 days, the eggs hatch, and the chicks rely on their parents for food for at least 40 days.
After 75-80 days chick leaves the nest. Depends upon the food availability, secretory birds often raise more than one chick at a time.
Fun Facts About Secretary Bird!
The extremely long legs of secretory birds provide them a strange look but they adapted them for its terrestrial niche. There are many other interesting concepts about secretory birds.
Secretary Bird: a Terrestrial Birds
Instead of flying, they prefer running and spend most of their time moving around on foot. However, they are also able to fly but it requires a lot of energy. Therefore they fly without flapping their wings with the help of thermal columns to save their energy.
They prefer moving on the ground due to the difficulties in flying and prefer flying only if necessary such as they fly to perform courtship rituals and to reach their nests.
Besides secretory birds, the kiwis, ostriches, and penguins also adapted themselves to the terrestrial lifestyle. These all species have not any related taxonomic group that clears that they lose their flying ability because of numerous occasions throughout history.
Unique hunting technique They usually hunt their prey by using many unique techniques. For example, they stomp on vegetation to flush out animals inside the tall grass and then chase down their prey.
They use their feet or bill to strike their prey and can use a force up to 5 times their own body weight. It shows that they have adapted very well to this hunting style. Due to their short toes, the secretory birds have limited grasping ability.
Therefore they cannot carry their prey away in their feet as other birds of prey usually do and eat it immediately. Sometimes they tear it apart using their feet but usually, they eat their prey whole.
Secretary Bird: The Archer of Snakes
The secretory birds have a great ability to kill even dangerous venomous snakes with their stomping techniques, therefore they get the name Sagittarius serpentarious which means ‘archer of snakes’.
They can kill snakes including cobras and adders by their strong kick and also prevent themselves from the bite of their prey by other features.
For example, they have tough scales on the lower legs that protect them from bites, and their long wings distract their prey because the hollow feathers do not get affected by snake bites.
Secretary Bird Citations
- The fast and forceful kicking strike of the secretary bird. Curr Biol . 2016 Jan 25;26(2):R58-R59.
- Tracheal Resection in a Secretary Bird ( Sagittarius serpentarius) with Granulomatous, Foreign-body Induced Tracheitis. J Avian Med Surg . 2017 Dec;31(4):308-313.
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Cuckoo: Description, Habitat, & Facts
Continue ReadingCuckoo Classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Cuculiformes
Family: Cuculidae
Genus: Cuculus, 25 others
Cuckoo Description
Medium-sized bird, cuckoo belongs to family Cuculidae. The family includes more than 24 genera of slender birds including roadrunner, European cuckoo.
They are distributed throughout the world. Some species of cuckoo such as roadrunner spend much of their time in the ground and while most of the members are tree-dwelling.
Cuckoo Appearance
The bronze cuckoo is the smallest member of this family, which weighs only 0.03 lbs and has a length of about 6 inches whereas the channel-billed cuckoo, which is the largest species weighs up to 1.4lbs and have 25 in length.
The European cuckoo is a common and well-known species, which is 32 cm in length. The body of the common cuckoo appears greyish in color whereas some females and juveniles also show a red-rust or rufous color morph.
The tail of the cuckoo makes about 40 percent of its overall length and the belly feathers also present on their frontside that are barred black and white. Common cuckoo molts twice per year.
The members of the cuckoo family display a variety of traits and behaviors but still, they have some common traits.
For example, their feet are the significant distinguishing feature, which includes four toes among which two inner toes point forward while two outer toes point backward.
The condition is called ‘zygodactyl’. The members of the family Cuculidae consist of species having two general body forms named arboreal and terrestrial species.
The arboreal species including the common cuckoo have a slender body with shorter feet and are tree-dwellers. The terrestrial species have different body forms with larger feet and have rounder and heavier bodies.
The example includes roadrunner that spends their time on the ground and prefers running instead of flying. Due to their heavier body flying is not a viable option for terrestrial cuckoos.
Cuckoo Distribution
Cuckoo belongs to a large family and is distributed all over the world on every continent besides Antarctica. The brood parasite cuckoos from sub-family cuculinae are one of the most broadly distributed sub-family, which occur across Asia, Europe, Australia, and Oceania.
The different species have different habitat preferences such as arboreal species are primarily tree-dwellers and terrestrial species prefer to live on the ground. They select their habitat based on food availability and safety to form a nest and breeding.
Some species prefer arid deserts or less vegetated areas to live in, e.g. the greater roadrunner. Most of the species tend to remain in their tropical paradise but some species prefer seasonal migration while some others migrate within their range.
The example includes the long-tailed koel, which breeds in New Zealand but in winters it migrates to grounds of Polynesia, Melanesia, and Micronesia. Most cuckoo species feed on insects mainly on caterpillars.
Cuckoo Nesting and Reproduction
The breeding habits also vary among species of the cuckoo family. Most species including roadrunners are monogamous. They build their nests in trees while the terrestrial species from a nest on the ground.
The common cuckoo finds a perch to settle on during the breeding season. The cuckoo drops its wings at its side by raising its long tail. Some of the species resort to brood parasitism while the majority of species raise their young ones on their own.
The parasitic birds lay just one egg in the host species’ nest whereas non-parasitic birds lay up to 6 eggs in their own nest. The distribution of these species is worldwide.
Some species are threatened from habitat destruction or human development but most of the species are not threatened. The IUCN Red List for threatened species listed them as “Least concerned” species.
Fun Facts About Cuckoo!
Human culture has interacted with Cuckoos for millions of years, from ancient Greece to the Europe of Shakespeare to India and Japan.
Cuckoo is a Parasite Bird
The category of brood parasites includes common cuckoo and other members of the subfamily Cuculinae. The young ones of these species are reared by other species. When the owner of a nest is out for hunting or defending its territory, the female cuckoo lays her egg in its nest.
The males also do the bidding for females in some cuckoo species by luring the host species away from its nest. The other bird incubates the egg of the cuckoo and also feeds the cuckoo chick after its birth.
The cuckoo chick often pushes other eggs and chicks from the nest and takes over. Warblers are also one of the host adults that are much smaller than the large cuckoo chick.
In some cases, the young of these brood parasite species have cryptic plumage (feathers) at a young age and the plumage resembles similar to the host species. Some cuckoo eggs will also mimic the eggs of the host species.
Cuckoo: a Communal Bird
The cuckoo is a monogamous organism. However, several species of cuckoo show brood parasitism. This interesting behavior is only seen in the members of the cuckoo family.
However, besides brood parasitism, one another behavior is also seen in some species. The anis cuckoo and the guira cuckoo and some other species also lay their eggs in communal nests.
The large nest was built by all the members of the group and then used by all to rear their young. But the system has also some problems like many communal situations.
The females have competition between them to remove other eggs from the nest to lay their own.
Cuckoo: an Advanced Repertoire
The diverse calls and songs of cuckoo are well-known. They are secretive and deceptive birds and communicate via their variety of songs. They also announce their dominion and attract their mates with songs.
Interestingly, over vast geographical ranges, the songs remain highly consistent. But instead of learning from their parents, they may be innate to a species due to their communal raising.
Cuckoo Citations
- Parasitic cuckoo catfish exploit parental responses to stray offspring. Philos Trans R Soc Lond B Biol Sci . 2019 Apr 1;374(1769):20180412.
- A melanocytic cuckoo. JAAD Case Rep . 2018 Apr 6;4(4):384-385.
- A cuckoo in the nest. New Sci . 2020 Apr 11;246(3277):32.
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Embalming: Definition, Types, & Examples
Continue ReadingEmbalming Definition
Embalming is an ancestral practice that employs chemicals to inhabit the decomposition of human remains to preserve them for social rites or educational purposes. It has 3 goals and preserves the entire physical body. These goals include:
Sanitization: The body is thoroughly cleaned by utilizing disinfectant and anti-microbial solutions. This helps to reduce any unwanted foul odors and delay the process of decomposition.
Preservation: The circulatory fluids like the blood and lymph are emptied from the body to preserve it and then it is pumped with embalming fluids. These chemical fluids decrease the rate of decomposition and preserve it in the recent condition.
Presentation: This involves preparing the body and making it more visually pleasing and presentable for social events like a funeral. The body is staged by massaging of limbs to decrease effects of rigor mortis, hair is styled, the body is shaved, facial expressions are set, they are dressed, and make-up is applied to give a lifelike appearance.
Embalming Process
This has been practiced since ancient times and has been a part of religious and cultural rites. The techniques and tools for this practice have evolved and may differ regionally. This process begins by positioning the body in a supine position with the head slightly elevated. The various material or tools employed in this practice are given below:
Step 1: Verification of Death: It is assessed first whether the person is dead. To verify this rigor mortis, clouded eyes, general unresponsiveness, and absence of pulse are some features that are checked. The identification of a deceased person is ascertained by foot and hand tags.
Step 2: Wash and Massage the Body: The body is stripped and the personal effects are removed, then employing an antimicrobial detergent the body is sanitized. Orifices like the mouth are carefully rinsed. Massaging of limbs removes their stiffness.
Step 3: Setting the Features: A specialized eye cap is utilized to pose the eyes by the embalmer. Then the lips are closed shut by using an adhesive, wiring, or suturing. Any visible strands of hair are removed by shaving.
Step 4: Injection of Embalming Fluid: Various chemicals are injected to temporarily preserve the state of the body. These chemicals are injected into the peritoneal cavity and vessels of the body via different methods.
Step 5: Application of Cosmetics: The embalmer applies cosmetics and moisturizer to give the skin a more lively appearance and to hide any discoloration. They can refer to a recent photograph provided by the family members.
Lack of circulation can result in discoloration of the face, which can be corrected by using make-up that adds depth and color to the skin. Hair is often styled and perfumed oils and gels are often applied to mask the odor. Then the body is dressed in formal clothes.
Embalming Fluid
Arterial embalming: Under this process, the embalming fluid is injected via a centrifugal pump into the carotid artery which displaces blood and causes it to drain through the right jugular vein.
Following these, the vessels are properly massaged to prevent the formation of clots and to uniformly distribute the fluid. A single-injection may be enough or in some cases to ensure even distribution they are injected at multiple sites.
Normally a body can hold up to 2 liters of embalming fluid. A specialized machine pumps this chemical into the blood while monitoring the pressure of vessels. Lastly, a hypodermic needle is used to fill any location that is left.
Cavity Embalming: In this, an incision is made above the navel and the abdominal cavity is performed. Then a trocar is inserted into this cavity through the incision and the contents of organs are aspirated.
Employing a concentrated embalming fluid the peritoneal cavity is filled. After which it is sutured or employing a trocar button the peritoneal cavity is shut.
Surface Embalming: In this method, the embalming fluid is applied to the skin surface that helps to deter the damage caused during the autopsy, or any cancerous disease or as a result of organ donation.
How to Become an Embalmer?
An embalmer would require education in areas of human physiology and anatomy, chemistry, mortuary practice, and embalming methods and theory. They are certified after a practical examination and are often affiliated with a professional embalming society.
In certain regions, embalming may be performed by the doctors themselves and no embalmers are required. Morticians may also practice embalming.
Embalming Citations
- Thiel embalming method for cadaver preservation: a review of new training model for urologic skills training. Urology . 2015 Mar;85(3):499-504.
- The antimicrobial capacity of embalming solutions: a comparative study. J Appl Microbiol . 2019 Mar;126(3):764-770.
- Is thiel embalming worth the risk? Am J Surg . 2021 Aug;222(2):459.
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Perspiration: Definition, Function, & Examples
Continue ReadingPerspiration Definition
Perspiration is the process that involves the secretion of fluid like sweat from sweat glands. As it is both a verb and noun as it can refer to the sweat produced or the very act of sweating.
Sweat is comprised of water, lactic acid, urea, and other minerals. This process can only be observed in mammals, but some mammals like humans, horses, etc. sweat more as they have more sweat glands.
Humans have around 2-4 million sweat glands. This physiological process helps in bringing down the temperature of the body.
What is Perspiration?
Perspiration is a means of thermoregulation in organisms like humans and other primates that have many sweat glands. It functions to maintain normal body temperature irrespective of the temperature of their surrounding. Sweating helps lower its body temperature as the sweat evaporates from the body.
In other mammals that have fewer sweat glands, perspiration plays only a minor role in thermoregulation. For instance, dogs do have few sweat glands on their feet pads that help them to feel cool but they use panting as a mechanism for thermoregulation as the water evaporates from the throat and mouth.
Another example is rhinos and pigs where sweating alone is not sufficient so they wallow in mud that helps lower their body temperature. Hippos spend most of their time in the water to stay hydrated and cool as true sweat glands are absent in them.
Cetaceans like whales and porpoises also do not have sweat glands and depend on water for maintaining their temperature.
Types of Sweat Glands
Two types of sweat glands include apocrine and eccrine. Eccrine sweat glands can be located all over the body and they are numerous in number. They secrete odorless sweat and consist of salt and water.
They are usually found in the large numbers on the soles of feet, palms, and head. Apocrine sweat glands are located only on specific sites on the body like ear canals, armpits, and genitals and produce odorless sweat.
The particular smell or scent of body odor occurs as a result of bacterial decomposition. These glands are also sensitive to the concentration of adrenaline so humans perspire more when they are stressed, or in pain or fear, or experience sexual arousal.
The ceruminous gland and sweat gland secretions may differ in many Asian people due to a mutation in the ABCC11 gene due to which they produce less body odor than others. They also tend to have dry earwax. As ceruminous glands are modified sweat glands, the same gene affects their functioning also.
Hyperhidrosis
It refers to excessive perspiration condition also known as diaphoresis or hidrosis. It can be of 2 types: primary or secondary. Primary hyperhidrosis is present from birth and it is general in nature that involves all the body.
Secondary hyperhidrosis is acquired due to disorders like thyroid or menopause and can be localized to a specific site. Stress or anxiety may incline the symptoms of the primary type as the sympathetic nervous system is involved which leads to greater perspiration.
Treatment of Hyperhidrosis
Primary hyperhidrosis is treatable with many treatment options. Clinical strength deodorants can be prescribed that comprise a higher quantity of aluminum chloride than other deodorants.
Another type of treatment is iontophoresis whose mechanism is not well understood but is effective and in use as a treatment method since the 1940s. In this technique feet or hands are immersed in water that has a low electrical current passing through it.
Anticholinergics prescription can also be taken orally before a stressful event but can have side effects like constipation. Botulism toxin injections can also give temporary relief that lasts 9 months.
Sugary can be a last resort method if no other technique is working; sweat glands are removed or sympathetic nerves that supply to these are impaired. There are also some side effects to this method as the person may sweat more from other parts. The removed nerves may also regenerate after surgery.
Affected people may adapt to new lifestyle changes required to decrease sweating like wearing breathable fabrics that are loose fit, bathing often, and consuming less spicy food and alcohol.
Perspiration Citations
- Cholinergic induction of perspiration attenuates nonhistaminergic pruritus in the skin of patients with atopic dermatitis and healthy controls. Br J Dermatol . 2015 Jul;173(1):282-4.
- Electrochemical tattoo biosensors for real-time noninvasive lactate monitoring in human perspiration. Anal Chem . 2013 Jul 16;85(14):6553-60.
- Developing a new device for continuously recording, in vivo, the excretion rate of sweat (perspiration) in humans. Skin Res Technol . 2019 Jul;25(4):489-498.
- Perspiration. Indian Med J . 1946 Jul;40:196-8.
- Images are created with BioRender.com
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Shoebill Stork: Description, Habitat, & Facts
Continue ReadingShoebill Stork
Shoebill Stork is an endemic species belong to the genus Balaeniceps and comes under the order Pelecaniformes. They are terrestrial piscivores that are endemic to wetlands and swamps of East and Central Africa.
This solitary bird comes from its huge bill that resembles shoes and also possesses huge wings. It is hypothesized that they are related to dinosaurs. These ancient-looking birds have white/grey or yellow piercing eyes and a white belly.
Shoebill Stork Characteristics
Shoebill Stork’s enormous wing can span up to 8feet while soaring and they have a blue-grey, dark grey, or slay-color plumage. They can be found near papaya swamps or overspill areas, where there are a lot of fishes that serve as their primary food source.
They are usually diurnal but may also hunt at night if enough moonlight is available. They also prey on frogs, baby crocodiles, water snakes, young turtles, and monitor lizards. They built their nest out of plant materials on top of floating plants in deeper parts of the swamps.
The vegetation around the nests provides cover against predators. They have an average clutch size of 2-3 eggs and the young attain sexual maturity at 3-4 years.
Shoebill Stork Breeding
Shoebill Stork birds are monogamous that share parental responsibility. The eggs are incubated for a period of 30 days, wherein they are frequently turned by the parents using their feet or bills.
The chicks have a silvery-grey thick down that has a wide gape. They show growth of large bills only after a year. They are fed mashed food by both parents.
After a month, they will be fed with prey items. At the end of 95 days, fledging occurs and they become independent by 125 days.
Fun Fact about Shoebill Stork!
Shoebill Stork is an ancient birds, have been known to humans for a long. They were described first in ancient Egypt. They show some intriguing biological concepts.
Shoe-shaped Bill: The characteristic shape of the bill helps them in acquiring their primary food source. This huge beak that is shaped like shoes span 20 to 24 cm long and is 10 to 12 cm wide.
These bills are employed for hunting and grasping the slippery large fishes. The bill has adapted to develop a curved razor-sharp hook that is employed to spear the fishes in a unique manner called ‘collapse’.
They wait along the sides of the swamp detecting motion in the water while standing motionless. On detection of the prey they lunge towards with wings spread, it dives bill first and catches its prey.
After that, it holds up its head and grinds the edges of its beak to kill the prey. It also helps in clearing of other times like vegetation or water that was taken in along with the prey to be spilled out.
Urohidrosis: It comprises a cooling technique employed by pelicans, storks, and shoebills. This method involves sweating to cool down the temperature of these birds.
Shoebill storks to lower their temperature will defecate liquid water on their lower extremities that are legs. This waste comprises urine and feces that cools the legs as it evaporates. This technique is amazing as it is also a preventive measure.
The white powdery substance left after evaporation shield the legs from sunlight.
Siblicide: Birds like other animals also have an aim of survival and reproduction. They can either conserved their energy on small clutch size or they might have a large brood that also increases their survivability.
Birds may be monogamous or promiscuous. Certain birds practice siblicide where they kill their siblings to increase their probability of survival.
Birds like herons, egrets, boobies, pelicans and shoebill stork practice this. The eggs of shoebill stork hatch asynchronously. As a result, the first to hatch will be better fed as it has no competitors and so will develop quickly.
When other chicks hatch the parents do not distribute food equally as a result the chicks compete over food. The elder chick will resort to bullying as a consequence the younger chicks may die from wounds or starvation.
This strategy helps the parents to focus on one chick and increase its chance of survival so that it can become mature and pass on its genes. The clutch size is 2-3 eggs as some eggs may at times be infertile or damaged, in such a scenario they are still able to produce offspring.
If the availability of food increases then the aggression in the siblings will be decreased and as a result more chicks will fledge.
Shoebill Stork Citations
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Snow Leopard: Description, Habitat, & Facts
Continue ReadingSnow Leopard Definition
Snow Leopard is a carnivorous solitary big cat belongs to the genus Panthera and comes under the order Carnivora. This alpine cat is found in the mountains of Central Asia and weighs around 35-55 kg.
In some countries like India and China, they are found in higher altitudes while in Russia and Mongolia they are found in lower altitudes. They prefer the ravines, cliffs, and rocky outcrops that have rugged terrain as it can give them a good cover and also a clear view of prey.
In the sub-alpine and alpine zone they live in, they can easily travel in this thick covered layer of snow due to their adaptations in form of large paws.
Snow Leopard Behavior and Ecology
They are crepuscular animals that are active during dusk and dawn. These carnivorous cats ambush their prey while actively hunting. Their prey includes goats like argali sheep, wild sheep, and wild sheep.
They also hunt smaller mammals like voles, hares, and marmots. They form opportunistic hunters and may also hunt livestock or carrion. They can survive on a single large prey for up to 2 weeks. They are solitary animals, that may come together for mating during the breeding season and young cubs often accompany their mother.
They occupy large home ranges and mark them by urine scent marks. These territories can range up to several hundred square kilometers and they patrol these regions regularly.
A large home range ensures food availability. The home ranges of males do not overlap but the home range of a male can overlap with the territory of females.
Snow Leopard Reproduction
Snow Leopard’s breeding season is towards the end of winter and the resulting cubs are born between April and June. They give birth to 2 – 3 cubs inside a rocky den lined with a fur shed.
The cubs are born blind, but at the end of 1 week they can open their eyes and by 10 weeks they are fully weaned. They may leave the den when they are 2-4 months old, but they accompany their mother till they are 18-22 months old. When they are old enough to leave they search for large hunting grounds.
Fun Facts about Snow Leopards!
Snow Leopards is a carnivorous predators, show some interesting biological behaviors and concepts.
No Roar: The genus Panthera is comprised of tigers, jaguars, lions, and leopards. But one characteristic that sets them apart from the other species of this genus is that they are unable to roar.
It was thought earlier that the incomplete ossification of the hyoid bone produces the ability to roar but this feature is also present in snow leopards. But it is known now that the specific morphology of vocal folds in the larynx is responsible for this ability that is lacking in snow leopards.
They communicate using other sounds like purrs, growls, and hisses similar to other big cats. It was earlier thought these cats were the first to diverge within the genus Panthera, but it has been recently established that it actually forms a sister clade with tigers.
These 2 groups diverged between 4.62 and 1.82 million years ago and further diverged from each other around 3.7-2.7 mya. The ability to roar might have been an ancestral feature that got lost in snow leopards after their divergence.
Alpine Adaptations: As they are native to cold alpine habitats, they have adapted and evolved various adaptations that aid in their survival.
Snow leopards have dense woolly underfur, long hair, round and small ears. These features aid to conserve body heat and reduce heat loss. These features can also be seen in arctic foxes and polar bears.
Other adaptations include long thick tails that they wrap around their body to keep warm and an enlarged nasal cavity that helps to warm the air before it enters the lungs. They also exhibit adaptations that help them to live on rugged mountainsides.
They possess long tails and short forelegs that help them to keep their balance. Their long hind legs aid them to jump up to 30 feet during hunting. Their light-colored fur along with dark spots also helps them to camouflage with the mountains.
Apex Predator: These big cats are apex predators and form the topmost trophic levels and do not have natural predators. Other examples of apex predators include sharks, crocodiles, and eagles.
They can exert top to bottom influence on ecosystems as they can check the population of other prey and predators. Human interventions in form of poaching of apex predators can trigger a trophic cascade where population sizes of lower food chain species are dramatically altered.
This will lead to changes in biodiversity, effect on ecosystem structure, and nutrient cycling.
Snow Leopard Citations
- Range contraction of snow leopard (Panthera uncia). PLoS One . 2019 Aug 1;14(8):e0218460.
- The snow leopard‘s questionable comeback. Science . 2018 Mar 9;359(6380):1110.
- Prey preferences of the snow leopard (Panthera uncia): regional diet specificity holds global significance for conservation. PLoS One . 2014 Feb 12;9(2):e88349.
- A spotlight on snow leopard conservation in China. Integr Zool . 2016 Jul;11(4):308-21.
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