Category: Biology
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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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Mesentery: Definition, Function, & Examples
Continue ReadingMesentery Definition
Mesentery envelops the organs of the gut and helps in their suspension from the abdominal wall. They are comprised of mesodermal cells that are derived from the middle layer of the 3 germ layers.
It surrounds all internal organs as it forms the peritoneum. This layer folds over itself in the gut, and aids in providing attachments for internal organs. The mesentery was earlier thought to be comprised of different tissue associated with mesocolon.
Recently it was discovered to be a single organ that aids in the suspension of organs in the abdominal cavity and facilitates the supply of vessels to these organs.
Mesentery Anatomy
The mesentery due to its thin convolutions and folds was not originally considered an organ. It encloses organs of the abdominal cavity. As it is formed during embryonic development it gets convoluted as the gut forms and develops.
This explains the complicated structure of mystery that is red. This organ is very thin and comprises very fine sheets of tissue that encloses organs and folds on itself. Mesentery comprises many lymph and blood vessels that supply to organs.
Mesentery may appear similar to connective tissue microscopically. This organ consists of mesodermally derived cells linked to connective tissue matrix.
This leads to a strong fiber and cell network due to the presence of an extracellular matrix that can repair itself if damaged. Lymph and blood vessels travel through this structure to reach the intestines.
Mesentery Function
Within the convulsion and twisted folds of mesentery tissue immune cells, blood vessels, and lymph vessels are arranged in a complex manner. This also reveals some functions of this structure that aids in the transportation of nutrients away via blood from the intestines and also providing protection against any sort of infection.
This organ provides for a secure passage for these vessels so they can distribute the nutrients absorbed in the intestine to the rest of the body. If mesentery were absent, then these vessels that are fragile in nature may be subject to wear and tear due to stretching and pulling.
Lymph vessels can also access the intestines through the mesentery. Along with food certain pathogens and other microbes may enter our body and find their way to the intestines. Lymphocytes and other WBC’s provide defense against such invaders and help to eliminate them from the system.
The supply of lymph vessels serves this purpose. Other than its roles in protection and providing passage for vessels, it also is involved in the development and support of the gut. The contractions, convulsions, and expansion of mesentery and its folds guide the shape of the gut to form.
For instance, the colon is positioned by pulling into a site against the abdominal wall by shrinking of the connecting mysteries. If there was no mesentery then all organs might have fallen into the bottom of the gut in a puddle as mesentery helps them to hold them in place by providing attachment points.
Mesentery also has nerves stretching to the internal organs like the intestines and it also holds excess fat. must be done. It may also contribute to other functions, besides in development and immune defenses that have not been discovered yet and needs more research.
Mesentery Disorders
Scientists have found several diseases associated with the dysfunction of the mesentery. It is involved in the defense line against food-borne pathogens but may also aid in spreading diseases like cancer.
As it may provide a passage for metastasizing cancer through blood or lymph vessels. This central highway of distribution may be investigated for cancer treatments. A dysfunctioning mesentery may also cause diseases like other diseases, such as Crohn’s disease, which are caused by a malfunctioning mesentery.
People with Crohn’s disease often have a swollen or hardened mesentery. This makes it difficult for the vessels contained in the mesentery to function properly. People with this condition often have a hard time digesting food and can have compromised immune systems.
Mesentery Citations
- The mesentery as the epicenter for intestinal regeneration. Semin Cell Dev Biol . 2019 Aug;92:45-54.
- Mesentery – a ‘New’ organ. Emerg Top Life Sci . 2020 Sep 8;4(2):191-206.
- The Mesentery, Systemic Inflammation, and Crohn’s Disease. Inflamm Bowel Dis . 2019 Jan 10;25(2):226-234.
- The mesentery: structure, function, and role in disease. Lancet Gastroenterol Hepatol . 2016 Nov;1(3):238-247.
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Harbor Seal: Description, Habitat, & Facts
Continue ReadingHarbor Seal
Harbor Seal is a solitary carnivorous mammal, belongs to the genus Phoco and order Carnivora. These marine organisms have a life span of 25-30 years and weigh up to 140 kg.
They occur at a wide range of temperate coastal regions spanning along the east and west coast of North America and the west coast of Europe.
Harbor Seal Features
Harbor seal can measure up to 5-6 feet in terms of length. They lack pinnae or external ears and have a round large head. They have characteristic V-shaped nostrils that are surrounded by whiskers and have smooth skin that depending on the species may be spotted or mottled or may be grey or white in color.
Their flat long flippers along with the hindlimbs endorse them with swimming abilities. They are not able to move very well onshore and do not wander far from the water’s edge.
Harbor Seal Habitat
These species of pinniped are widely distributed along the temperate coastal regions. They are distributed along both arctic and temperate coastal regions of the Northern Hemisphere.
This includes the part of the northern Atlantic and the east coast of North America. In these coastal habitats, they dwell within the shallow waters of lagoons, estuaries and marinas. They may haul out of waters often to nurse their offspring or to rest.
They form social groupa that are loosely formed for purpose of defense but otherwise these animals are solitary.
Harbor Seal's Prey and Predators
These marine carnivorous prey on fishes and smaller invertebrate species mostly. When hunting they can travel up to 30m and may even reach freshwaters searching for frrding grounds or prey like salmon. They also dive deep into the waters at a depth of over 1,500 ft to look for prey.
Some of their preferred prey include anchovy, shad, mackerel, cod, herring, sea bass etc. In absence of fish they may also hunt for invertebrates like mollusks like giant Pacific octopus and crabs.
They have many predators in the marine sea include orcas, shark, sea lions. They are hunted in the waters by orcas but they may also snatch pups on shores. Sharks also feed on pups, some sharks also prey on adult seals like Great White Shark.
Great White Shark jumps high and breeches the surface in search of seals. Sea lions also prey on small seals. Other predators that pose threats for them include wolves, bears, coyotes, and eagles that specifically target pups.
Harbor seals often form groups in familiar haul out sites to evade predation from them. They have also been poached by humans for their pelts and blubber. Now, their hunting is illegal in almost all of its habitats.
Harbor Seal Reproduction
The gestation period in harbour seals lasts 9 months after which they give birth to a single pup that weigh 35 pounds and are born largely on land. Within a few hours of birth these pups can dive and swim.
Females wean and take of the pups alone for 4-6 weeks. Captive seals may live longer than their average life span.
Harbor Seal Conservation Status
Their global population is estimated to be around 350,000 to 500,000 individuals. In threathened habitats some particular subspecies count are low. They are listed under the category ‘Least concern’ on IUCN Red List.
Fun Facts about the Harbor Seal!
Harbor Seal are ubiquitous in their habitats and are observed by humans for their playful nature. They are included in large aquaria due to their nature and are fascinating creatures.
Fat is a Friend: The body heat quickly dissipates as they spend a lot of time in cold waters. In harbour seals as an adaptation they have evolved thick layers of sub-cutaneous fat that serve dual purpose to provide insulation as well as to provide a quick source of energy when there is scarce food availability.
They have higher resting metabolism rate that is 1.7-2.2 times higher than other mammals. To build and maintain this insulation fat energy reserve layer they need to ingest high calorie intake preys.
Holding its Breath: It has evolved various adaptations besides the fat layer that helps in their survival in marine waters. They have webbed flippers that help them to swim efficiently and at a quicker pace.
They can dive up to an extraordinary depth of up to 1,500 feet that is amazing for an air breathing mammal. They like other marine mammals keep their lungs filled to full capacity before diving and underwater they stop breathing.
Their low heart rate helps them to conserve oxygen and this reduces the formation of lactic acid in their muscles. Their narrow nostrils also remain closed during the time they dive, that is also an adaptation.
Same Same but Different: They are monomorphic and different subspecies differ in respect to their skin color. Based on their coat color they may be light phase or dark phase. Light phase seals have yellow-cream coat that are covered in black spots. While dark phase seals have black coat with light rings.
The existing different colour patterns can be a result of differing depositions of melanocytes in their epidermis primarily due to their different diets.
Harbor Seal Citations
- Mechanical properties of harbor seal skin and blubber – a test of anisotropy. Zoology (Jena) . 2018 Feb;126:137-144.
- Trophic ecology of Mexican Pacific harbor seal colonies using carbon and nitrogen stable isotopes. PLoS One . 2020 Jan 22;15(1):e0225889.
- Spontaneous rhythms in a harbor seal pup calls. BMC Res Notes . 2018 Jan 3;11(1):3.
- The Pacific harbor seal gut microbiota in Mexico: Its relationship with diet and functional inferences. PLoS One . 2019 Aug 29;14(8):e0221770.
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Dimetrodon: Description, Habitat, & Facts
Continue ReadingDimetrodon
Dimetrodon is a early mammal-like reptile belongs to the genus Dimetrodon and Order Pelycosauria that lived 280-260 mya in the Permian period. These predatory carnivores were earlier grouped with dinosaurs due to their resemblance with them, but they are more closely related to mammals and they got extinct 40 million years before the dinosaurs. There are around 15 known species in this genus.
Dimetrodon Features
Dimetrodon genus displays many mammal-like features and is adapted to a range of habitats. Its fossils have been located around Oklahoma and Texas in the US, Canada, Nova Scotia, and around Europe as well.
The first fossil was discovered by Edward Drinker Cope during the 19th century. It is difficult to ascertain the habitat they preferred as Earth would have looked different then. Based on the places their fossils were found, these animals were adapt from arid dry regions to wetter areas like swamps.
This cold-blooded reptile walked on 4 limbs. It also possessed a large tail that contributed to the large proportion of its body length. With its large tail, it might have moved like present-day crocodiles. They were also sexually dimorphic with males being larger than females.
Dimetrodon had sharp large teeth that were adapted for carnivores, so scientists conclude they were meat-eaters, but could not ascertain their prey. They were egg-laying reptiles but no further information is available about their reproduction strategy.
Fun Facts about the Dimetrodon!
The Dimetrodon existed millions of years before dinosaurs evolved and they are mammal-like reptiles. Several adaptations employed by this organism have been found out by scientists that link them to mammals.
Thermoregulation: The large sail on the back of the Dimetrodon was one of its distinctive features. This sail was speculated to be a vascularized membrane that was employed for thermoregulation. It might have helped to absorb heat during the day and utilizing this heat to keep warm at night efficiently due to its surface area.
Employing this would make them more efficient in warming up and would become active sooner than another organism. This adaptation would help it to hunt for other sluggish organisms.
The sail might also have roles in warding off predators or in courtship rituals. This sail is also seen to have evolved independently in the Edaphosaurus which was also Peltcosaurs and a distant relative of the Dimetrodon.
Ziphodont Teeth: It is named for having 2 different types of teeth that include canine teeth and shearing teeth. They were the first terrestrial organisms to possess laterally compressed teeth that were sharp and had serrated edges known as ziphodont teeth.
The different species of the genus Dimetrodon had varied ziphodont teeth. The teeth of 3 species of Dimetrodon that existed during different times were examined.
Dimetrodon milleri was the smallest and oldest species and its teeth were straight and sharp with cutting edges. Dimetrodon limbastus was larger than the other species and had small serrations on the enamel of its teeth. It came later in evolution, and their teeth were much better suited to cutting the muscles and skin of the meat.
The final species Dimetrodon grandis had teeth that resembled teeth of predatory dinosaurs and they had prominent denticles that were specialized for cutting meat.
The trends in the evolution of specialized teeth suggest they were equipped to hunt various kinds of prey. The teeth might have evolved to widen their range of prey and also to help them hunt larger animals.
Are Humans Descended of Dimetrodon?
While these animals looked more like reptiles than mammals, they had certain characteristics that relate them to the earliest mammals and make them a distant relative of humans.
Dimetrodon skull possesses temporal fenestra which is a single large hole where the lower jaw muscles attach to the skull. This feature shows their similarity to synapsids that comprise modern mammals. Dinosaurs are diapsids as they have 2 holes in this region.
This suggested that even though they have some morphological similarities to dinosaurs they are distantly related to modern mammals. Synapsids and reptiles split from a common lizard-like ancestor 324 mya. Early synapsids might have resembled reptiles and later evolved.
Dimetrodon under synapsids belongs to the group sphenacodontians. What’s surprising is that this group also comprises another distant relative of modern mammals that has similar features to Dimetrodon.
Dimetrodon Citations
- Natural environment and thermal behaviour of Dimetrodon limbatus. J Therm Biol . 2001 Feb 1;26(1):15-20.
- Comparative anatomy and osteohistology of hyperelongate neural spines in the sphenacodontids Sphenacodon and Dimetrodon (Amniota: Synapsida). J Morphol . 2010 Dec;271(12):1407-21.
- Bone histology and microanatomy of Edaphosaurus and Dimetrodon (Amniota, Synapsida) vertebrae from the Lower Permian of Texas. Anat Rec (Hoboken) . 2021 Mar;304(3):570-583.
- Dimetrodon (Synapsida: Sphenacodontidae) from the cave system at Richards Spur, OK, USA, and a comparison of Early Permian-aged vertebrate paleoassemblages. Naturwissenschaften . 2019 Jan 4;106(1-2):2.
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River Otter: Description, Habitat, & Facts
Continue ReadingRiver Otter
River Otter is a carnivore mammal belongs to the genus Lontra and the order Carnivora. The species Lontra canadensis is the most abundant otter and is also known as Canadian otter or North American river otter.
These solitary otters have an average lifespan of 12 years and weigh up to 10 to 33 pounds. They can be usually found in North America in freshwater and marine habitats.
River Otter Description
On their lighter underside, they have grey or brown fur. Their short dense underfur is covered by coarse darker hair that helps to repel water. They have streamlined muscular bodies with short legs and webbed feet that have non-retractable claws.
They have long necks and small heads. Their tails comprise 40% of their body length and have muscular flattened tails. They are excellent swimmers as they have muscular tails and webbed feet that aid them to move swiftly through waters. They close their nostrils and ears before diving underwater.
They can stay up to 4 minutes underwater. They may live in pairs or maybe alone. They can extend their home range to be as large as 78 square kilometers but usually, they occupy much smaller territories that measure up to 3-15 square miles.
They mark their home range by defecating, scratching, urinating, or rubbing their scent glands on trees and rocks. The size of the home range varies according to their needs.
They form groups to socialize and have playful behavior. This playful behavior also adapts them to social skills like fighting and hunting.
River Otter Food
They are carnivorous nocturnal hunters. They prey on aquatic organisms like fish, insects, turtles, and small mammals. They may also hunt on land and may travel up to 18 miles foraging for food. They may hunt either alone or in pairs.
River Otter Mating and Predators
They make their dens in abandoned burrows or empty holes alongside the water. They prefer riparian zones as their habitat. These places will have underwater entrances such that they can access them from the water itself.
Their breeding season is late winter to early spring. The clutch size can vary from 1 to 3 pups that are blind when they are born. The pups are dependent on their mothers and in 2 months they learn to swim.
Their predators include alligators, bobcats, coyotes, and raptors. They became vulnerable due to pollution and habitat loss. Several groups have initiated programs to conserve natural populations.
Fun Facts about River Otters!
These underwater acrobats love sliding down just for fun, they are playful and have a social behavior. They have evolved adaptations that help to inhabit the environments they live in.
Thermoregulation and Metabolic Rate: These aquatic mammals inhabit a range of habitats ranging from temperate to very cold environments. It is harder to conserve heat energy underwater as heat conductivity can be 27 times faster than in air.
Aquatic mammals will lose heat rapidly even in warm waters. Otters counteract this heat loss by evolving a having higher metabolic rate up to 50 percent higher compared with similar size land mammals.
A greater metabolic rate helps to conserve and produce more body heat. This also demands more calories so otters might need to regularly ingest food.
Embryo Diapause: These aquatic mammals also have a physiological adaptation that ensures the survival of their young ones. Even though otters mate in early spring, the embryos formed do not attach to the uterus for 8-9 months, instead, they are free-floating and lie dormant in the uterus.
This strategy of delayed implantation is referred to as embryo diapause. This occurs so that females will not have to nurse their young during winters. The gestation in otters lasts 60 days, and the young are born in the following March.
This phenomenon is also seen in several other animals like seals, bears, and armadillos, where the embryo implantation is delayed till conditions are favorable.
For instance, bears breed during early summer or late spring. The females spend most of their time trying to increase their body fat.
When the required body fat has been accumulated, she will retreat to her den and then the eggs will implant. This method increases the survival rate of both the young and their mother.
Scent Communication: They employ their scent glands to mark their home ranges. These scent glands can be found at their tail’s end region; they also deposit their scent on dung that is known as spraint. T
his spraint is deposited along the boundaries of their territories in less visible regions like on boulders. These deposits may be found 40-70 meters apart. Each scent is different and unique and is informative of the age, identity, and sex of the otter.
Other animals like West African Civet, rabbits, and hippopotamus also use dung to mark their marker posts. Male hippos may engage their tails to distribute their excrement.
River Otter Citations
- Primary Pleural Squamous Cell Carcinoma in a Free-Ranging River Otter ( Lontra canadensis). J Wildl Dis . 2019 Jul;55(3):728-732.
- Metal contamination of river otters in North Carolina. Environ Monit Assess . 2020 Jan 28;192(2):146.
- The Gut Microbial Community Structure of the North American River Otter (Lontra canadensis) in the Alberta Oil Sands Region in Canada: Relationship with Local Environmental Variables and Metal Body Burden. Environ Toxicol Chem . 2020 Dec;39(12):2516-2526.
- Variation in Neotropical river otter (Lontra longicaudis) diet: Effects of an invasive prey species. PLoS One . 2019 Oct 3;14(10):e0217727.
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Fallow Deer: Description, Habitat, & Facts
Continue ReadingFallow Deer
Fallow Deer is a herbivore mammals belong to the genus Dama and the order Artiodactyla. They are seen in herds on sparse forests and grasslands of Europe and the Middle East. They belong to the family Cervidae that comprise reindeer, elks, and deer, etc.
They have characteristic shovel-shaped large palmate antlers and usually have a brown coat color with white spots. A range of genetic variations can be observed in them and they have an extensive range.
So besides the common brown coloration, varieties including Melanistic, Menil, and Leucistic also do occur. These color variations are influenced by several genes and their interaction with the environment they live in.
Fallow Deer Description
Males in early summer will start developing their antlers. Only 2 spikes can be observed in young bucks, that grow to become palmate antlers in a period of about 4 years. The antlers are significant to males, the males that possess the largest antler can defend their breeding territory or lek.
During rut that is a particular season in the fall, males attract females by defending a territory and this can earn them a chance to mate. After this season males shed their antlers that may be collected by mount creators in places where it is not prohibited.
They have an intriguing evolutionary history influenced by human history. They have been poached for sport and food from 500,000 years before in Paleolithic times, through the Roman Empire, and even today.
They have been introduced in many countries like South America, Australia, North America, and Africa. It may compete with the local native species in the regions they may have been introduced to.
Interesting Insights from the Fallow Deer!
They comprise a part of human history and demonstrate some important biological processes or concepts.
“The Rut” – A Timing Strategy
A rut specifies the timing in herd animals that have a mating cycle during which breeding season occurs. In the case of fallow deer and other related deer species, this starts in fall, following which the females gestate over in winter and give birth in spring.
The young will have much to feed on during the spring season. For the starting few months they feed on the milk of their mother, then with developing rumination, they acquire the ability to digest complex fibers of the plant.
They will then start to ingest huge quantities of leafy greens to grow in size. Females get sexually mature faster than males at 16 months, while males only mature by age of 4. The estrous cycle of the female is what drives the rut as they only come into estrous once every year.
This also means males get only limited opportunities and thus it tries to impregnate as many females as possible to increase the reproduction rate. Fallow deer bucks employ different kinds of strategies for attracting males, based on the population size and the local environment.
Fallow Deer Distribution
The population of fallow deer is distributed throughout the world and shows variations in these distinct populations. The ancestral population might have been brown. They were poached for food by humans for many thousands of years.
The red may have later evolved and expanded in Greece. These deers were brought to Europe where they evolved into the purple population that denotes Roman expansion. The teal population might be the modern form of fallow dear that might have emerged around the 1900s.
It has since then spread due to imports to South America, New Zealand, North America, Australia, and South Africa. They were originally native to Europe and the Middle East, and from there have been introduced to 4 other continents.
They are farmed often on ranches in places like Argentina and Texas. Their hunts may be sold to rich gun-owners, though there has been a decline in their hunting. Introduces species like these need to be monitored so they don’t impact the ecosystem functioning and destroy native species.
Fallow Deer and Polygyny
These fallow deer also exhibit polygyny like other cervids. They form groups of females heeded by 1 male. Whereas in polyandry, a group of many males is regulated by a single female as in fishes.
Polygynous groups have different rules and behaviors depending on species density, local behavior, and environment. Fallow deer exhibit 2 types of polygyny practices are Lekking and harem. In harem groups, the males stay with the group as they wander.
They tend to keep the females herded and will guard against entry or access of other males. In lekking, males defend the home range where the female is known as a lek. Only he can copulate with the female in his territory.
The local environment plays a key role which helps the male fallow deer decide on the polygyny practice it wants to engage in. If the environment is resource-scarce then the male forms harems so he may protect the female while they are foraging for food.
If the environment has abundant resources then the males will establish their territories where females hang out more. Defending territories is an energy-intensive process that can cause the deer to lose up to 17% of their weight during the rut season.
Fallow Deer Citations
- Molecular identification of two Sarcocystis species in fallow deer (Dama dama) from Lithuania. Parasitol Int . 2020 Apr;75:102044.
- Shiga toxin-producing Escherichia coli isolates from red deer (Cervus elaphus), roe deer (Capreolus capreolus) and fallow deer (Dama dama) in Poland. Food Microbiol . 2020 Apr;86:103352.
- Carcass and meat characteristics from farm-raised and wild fallow deer (Dama dama) and red deer (Cervus elaphus): A review. Meat Sci . 2018 Jul;141:9-27.
- Wild fallow deer (Dama dama) as definitive hosts of Fasciola hepatica (liver fluke) in alpine New South Wales. Aust Vet J . 2020 Nov;98(11):546-549.
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Peacock: Description, Habitat, & Facts
Continue ReadingPeacock
Peacock is an omnivorous polygamous bird belongs to the genus Pavo and Afropavo and order Galliformes. This ground-dwelling bird belongs to the same family as pheasants that is Phasianidae.
These semi-domestic birds exhibit characteristic fan-like colorful plumage. Out of the 3 species, 2 are native to Asia and one to Africa. They can be seen in parks and aviaries throughout the world.
Peacock Description
The term peacock is used for males and they are collectively called peafowl. It is the male members that exhibit distinctive feather fans near their rump. These colorful displays are made for the female.
The plumage is iridescent, the feathers exhibit shades of white, blue, bright green. When these feather fans are not displayed they follow the birds in a train manner. They may grow up to measure 140 to 160 cm in length and may weigh up to 6 kg.
A Congo Peacock
In the case of congo peafowl, no sexual dimorphism is observed in males and females. But green and Indian peafowl show sexual dimorphism.
Generally, females have plumage of brown and grey and are not as colorful as the males, and also do not have a trail train. They weigh around 2.8 to 4 kg and are smaller than males and measure up to 90-110 cm in length.
Peacock Distribution and Habitat
The 3 species of peafowl include Pavo cristatus, Pavo muticus, and Afropavo congensis. The Pavo cristatus or Indian peafowl is a common native bird of the Indian subcontinent.
The Pavo muticus or green peafowl is found in southeast Asia, while the Afropavo congensis or Congo peafowl is endemic to the Congo Basin of Africa.
They prefer forested regions as their habitat. They often utilize trees as a roosting area and shelter, where they spend their night safely. During the day, they move away from the roosting area in search of food.
Peacock Diet and Predators
They are omnivores birds and forage for seeds and flower petals or other plant materials. They also feed on small animals like amphibians, small reptiles, and insects. They spend their daytime foraging for food in leaf litter in open areas.
They scratch the dirt and debris to hunt for edible plant materials. They will retreat back to their roosting place in the forest during the hottest times of the day. The native places they occur are also home to their predators like tigers, mongooses, and dogs in Southeast Asia and India.
In the case of Africa, the Congo peacocks are preyed on by lions. Their eggs are also preyed upon and hence are vulnerable.
Peacock Nesting and Reproduction
Peafowl’s nests are found on the ground and they build these by scraping out small depressions and then lining them with soft vegetation and grass in the ground. These nests are well concealed among high grass and under bushes to avoid any predators.
The peafowl will often mate with many males over their lifetime and are polygamous. The males display their tail feathers and shake them in courtship for attracting females and often during this time they will also peck on the ground.
The average clutch size is 2-10 eggs. After copulation and a period of 4 weeks of incubation chicks emerge from the eggs. The chicks often display cryptic plumage of brown and yellow shades.
They stick by their mother’s side for 7 to 10 weeks. Peafowl sexually matures by 2-3 years and grow adult plumage. While the males attain sexual maturity by 4 years and they also grow out their feather fan.
Peacock Conservation
As these birds are common they are listed under least concern species on the IUCN Red List. While the rest of the species are popular and common in aviaries throughout the world, the green peafowl has since 2009 been listed as Endangered and the Congo peafowl has come under the vulnerable category.
The decrease of the forest area has caused some species to inhabit secondary growth forests as a potential conservation strategy.
Fun Facts about Peacock!
All About Plumage: The green peacock besides its iridescent plumage also has bronze and green feathers. This iridescent plumage gives them a metallic look. Eyespots can also be observed in their feathers that make them more colorful. In the case of green peafowls, both sexes possess colorful plumage.
Sexual Selection: The tail feather fan of males is an example of sexual selection that is a result of natural selection. The selection pressures favor the maintenance of certain traits that are favorable for the population and increase their survivability.
In the recent handicap theory that has been proposed the researchers postulate that these feather fans are a hindrance that fit males will overcome. Thus, it represents the fitness of the male.
A Change of Sex: Sexual inversions have been observed in peahens. They may exhibit bilateral gynandromorphism where the individual possesses sexual organs of both sexes and under genetic or environmental influences can undergo sexual inversion.
This process in peacocks may occur due to sex ratios or demographics. The exact mechanism behind this hasn’t been discovered yet.
Peacock Citations
- Characterisation of peacock (Pavo cristatus) mitochondrial 12S rRNA sequence and its use in differentiation from closely related poultry species.Br Poult Sci . 2007 Apr;48(2):162-6.
- Deceptive copulation calls attract female visitors to peacock leks. Am Nat . 2014 Apr;183(4):558-64.
- Isolation and characterization of peacock Chlamydophila psittaci infection in China. Avian Dis . 2011 Mar;55(1):76-81.
- Biomechanics of the Peacock’s Display: How Feather Structure and Resonance Influence Multimodal Signaling. PLoS One . 2016 Apr 27;11(4):e0152759.
- How conspicuous are peacock eyespots and other colorful feathers in the eyes of mammalian predators? PLoS One . 2019 Apr 24;14(4):e0210924.
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Albacore Tuna: Description, Habitat, & Facts
Continue ReadingAlbacore Tuna
Albacore Tuna predator belongs to the genus Thunnus and order Scombriformes. This pelagic fish can be found primarily offshore on temperate and tropical waters of the Atlantic, Indian and Pacific oceans comprising 6 distinct stocks.
They can grow up to 7ft in length and comes under the family Scombridae. They are commonly found in sport and commercial fisheries and have a lifespan of 10-12 years.
Albacore Tuna Description
Albacore Tuna fish has a streamlined body and at the end of its cone-shaped head, there is a largemouth. They appear silver-white on the ventral side and appear dark blue on their dorsal side.
They have large eyes and long pectoral fins. They have an anal fin and 2 dorsal fins and several finlets on their hind section and tail that make a larger caudal fin.
Albacore Tuna Distribution and Habitat
These 6 distinct stocks are distributed across the Meditteranean Sea, Indian, Atlantic, and the Pacific Ocean that makes them cosmopolitan. They prefer surface waters in the range of 50-77oF and may dive up to a distance of 2,000 ft deep.
They like other tuna species are schooling. They may either school with the same species or with other fishes like skipjack tuna who have a similar size to them. They do not mix with separate stocks and may travel great distances.
Albacore Tuna Diet
This fast-swimming fish is an excellent predator due to its largemouth, keen eyesight, and speed. But opposed to other tuna species that feed exclusively on fishes, they also prey on pelagic crustaceans, cephalopods like cuttlefish, squids, and octopuses along with fishes.
Albacore Tuna Reproduction
This tuna species is oviparous and its development occurs externally. Spawning occurs generally between November and February, females release a large number of eggs approximately 2 million at a time into the waters.
The males also simultaneously release sperms into the water. This synchronized release of gametes increases the probability of fertilization. After fertilization of the egg, the embryo formed is now a part of the zooplankton community that moves with the whim of the ocean currents.
Fry will always remain proximal to the spawning area, after 12 months they move on. They attain sexual maturity at the age of 5 to 6 years and have a life span of 12 years.
Albacore Tuna Conservation Status
Adults in this tuna species are highly migratory and travel great distances in the ocean. So as a stock, they can be difficult to manage due to their migratory tendencies. It is a task to regulate and protect their stock and requires international cooperation in policymaking and enforcement.
These fishes may be overfished due to their demand as they often are in great demand at sport and commercial fisheries. This species comes under the Near Threatened category of IUCN Red of Threatened species.
Fun Facts about the Albacore Tuna!
They may not be the most commercially valuable of tuna species, but this predator travels long distances and form a part of the GDP of various Pacific Nations. They have various interesting facts.
The Traveling Tuna: The migratory pattern of each stock of this species may differ. For instance, the North Pacific Stock travels between the temperate waters of the Pacific Northwest, British Columbia, and Baja California. While the North Atlantic stock migrates to the Bay of Biscay.
Fisheries management maybe even more complicated for tuna as they have vast ranges that involve different jurisdictions and require cooperation for effective management. The ecology and population dynamics may differ in different stocks.
For instance, older fishes are caught more often in catches made from cooler waters in the Atlantic Ocean, while in the Pacific Ocean the older fishes are found more often in warmer waters.
This can be understood in the concept of global climate changes that affect the ocean temperature that in turn affects the range, distribution, and spawning timings of the tuna stock.
Ever-Ready: These warm-blooded fishes rarely rest as it keeps its large muscles oxygenated at all time. This requires them to be on the move so that water can pass over the gills and the bloodstream may be oxygenated continually.
Asymmetrical Gonads: They generally have asymmetrical gonads. In the case of males, the right teste is larger and in females, the right ovary is larger. They also exhibit asynchronous oocyte development, the development of female eggs does not occur at a fixed frequency. So, at a time eggs will be at different stages of development.
Albacore Tuna Citations
- Optimal immobilization of trypsin from the spleen of albacore tuna (Thunnus alalunga) and its characterization. Int J Biol Macromol . 2020 Jan 15;143:462-471.
- Reproductive Biology of Albacore Tuna (Thunnus alalunga) in the Western Indian Ocean. PLoS One . 2016 Dec 21;11(12):e0168605.
- Connectivity and population structure of albacore tuna across southeast Atlantic and southwest Indian Oceans inferred from multidisciplinary methodology. Sci Rep . 2020 Sep 24;10(1):15657.
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