My Science School

Humans, apes, monkeys and lemurs all belong to a group of animals called primates. They have large brains, hands that can form a good grip, and a tendency to walk on two legs.

What do most living primates have in common?

• Large brains (in relation to body size)
• Vision more important than sense of smell
• Hands adapted for grasping
• Long life spans and slow growth
• Few offspring, usually one at a time
• Complex social groups

If one takes a look at the living primate species, one encounters an astounding variety of sizes, appearances and specializations so that one sometimes considers it incredible that we all have a common ancestor.  This common ancestor originated about 80 million years ago when the so-called Primatomorpha split up in the ancestors of today's colugos (Dermoptera) and the first primates. The closest relatives of the primates are therefore not, as long believed the Treeshrews (Scandentia), but cat-sized mammals, whose characteristic is a membranous structure that covers all its extremities and the tail that allows the animals to glide from tree to tree (Mason et al 2016). While only two colugos species are known in Southeast Asia, more than 500 primate species from 16 different families are known. The number of species has increased rapidly in the last 20 years due to the new possibilities of species differentiation using genetic methods 

Are humans descendants of apes?
For scientifically educated humans, it nowadays goes without question that all living beings are a product of evolution and that a common ancestor for all living primates including humans existed. The problem therefore seems to be of semantic nature: How do we call our common ancestors? The scientifically correct term would be "primate". In German-speaking science, the Anthropoidea, the group that has separated from the Tarsier after splitting of the “dry-nosed” primates, is referred to as the "real monkey" and in more recent literature only as "monkeys". These include all families of the American and Afro-Eurasian primates, including apes - and thus humans. If one referred to the first anthropoids that lived 64 million years ago as a monkey, one must logically assume that our ancestors of the last 64 million years were monkeys. However, there is only one logical answer to the question: not only are humans descendants of primates, but is one too.

Credit : German Primate Centre

Picture Credit : Google 

Yes, they are mammals and, after the South American capybara, beavers are the largest of all rodents. They live in water and use their sharp teeth to gnaw through the bases of trees, felling them to dam streams. In the ponds created by the dams they then build their homes, which are called lodges.

Beavers are mammals and have several mammalian traits. Beavers are vertebrates; they have mammary glands that they use to feed their live young, have a four-chambered heart, have fur, and have sweat glands to cool down.

Is A Beaver A Vertebrate?

One of the characteristics that all mammals have is that they have a backbone inside their body. However, it is not just mammals that have a backbone.

Other animals such as fish, amphibians, reptiles, and birds also have a backbone. Animals with a backbone are called vertebrates.

There is another group of animals called invertebrates. These are animals that don’t have a backbone inside their body. Examples include single-celled organisms, earthworms, starfish, octopus, snails, clams, insects, and spiders.

Beavers are classed as vertebrates with a backbone inside their bodies. The spinal cord is surrounded by cartilage or bone.

Beavers produce milk within their mammary glands. Beavers have four nipples, only visible when the female is lactating. This is one of the only ways to tell the difference between male and female beavers.

Beavers usually give birth to between one and six kits. Beavers are fully weaned off milk from their mother at about six weeks. The milk contains essential nutrients for beavers in the early stages of growing healthy. 

Does A Beaver Have A Four-Chambered Heart?

Mammals all share another characteristic, one which is also shared with birds. Both birds and mammals have a heart that contains four chambers. Surprisingly, crocodiles, a reptile, also have a four-chambered heart.

The four-chambered heart is essential for the respiratory system of mammals. When mammals breathe in air, they take in oxygen. Oxygen is needed to survive, but the waste product is carbon dioxide once the oxygen has performed its function. Carbon dioxide is expelled back into the air when we breathe out.

Do Beavers Have Hair?

Another characteristic of a mammal is that they have hair or fur. The fur is generally used when a mammal has very thick body hair. Humans have hair, but we wouldn’t call it fur, whereas other mammals covered, such as bears or raccoons, would have fur.

Hair or fur consists of two layers. These consist of a thicker underfur covered with oily guard hairs on top.  

The guard hairs are longer and coarser. They repel water from the skin and block the sun’s ultraviolet rays. In animals with markings, such as a jaguar, these markings are on the guard hair layer.

The thick underfur, or down fur, is used to keep the animal warm and is made up of curly or wavy hairs.

Even whales and dolphins have hair, although some species only have hair follicles. Species such as the humpback whale have hair their entire life, with a single hair coming out of each hair follicle.  Toothed whales usually lose their hair shortly after birth.

Do Beavers Have Sweat Glands?

Mammals need to regulate their temperatures, and although all mammals sweat, not all cool down the same way.

For us, sweating is a way of regulating our body temperature, so we don’t overheat. The sweat glands produce sweat, which evaporation carries away from the body. This carries away the heat and makes us feel cooler.  

Humans aren’t the only mammals that sweat through their skin. Primates and horses also sweat through sweat glands.

Do Beavers Have Three Middle Ear Bones?

Another trait that mammals possess is three bones in the middle ear. These three small bones are called ossicles and conduct vibrations (sound) to the eardrum’s inner ear.

The three bones are called the malleus (hammer), the incus (anvil), and the stapes (stirrup).

Once the vibrations are in the inner ear, the vibrations are converted into nerve impulses. These three bones play a vital role in a mammal’s hearing ability.

Credit : North American nature 

Picture Credit : Google 

Bats, of which there are more than 1300 species, are the second largest group of mammals. Megabats, also known as fruit bats because of what they eat, can have a wingspan of just under two metres. The flying fox is the largest bat. The smaller microbats are mostly carnivorous and eat insects; even small amphibians. Vampire bats are the only microbats that feed on animal blood.

More than 40 species of bats live in the United States. Bats are the only mammals that can fly. Instead of arms or hands, they have wings. The wings have a bone structure similar to the human hand. Between the bones are flaps of skin. Bats are very light weight to make it easier for them to fly. The western pipistrelle bat weighs less than a penny, while the greater mastiff bat weighs about two ounces (57 grams).

Bats have fur on their bodies, sometimes including their head. Their wings, however, do not have fur. Bats can be a range of colors, including red, tan, brown, and gray. A bat's ears are very important because bats use them to hunt for food. The ears tend to be large and noticeable, many times sticking up on the side of the head. The Allen's big-eared bat has ears so long that they make up two thirds of its body length.

The smallest bat in the United States is the western pipistrelle bat, which grows to about 2.5 to 3.5 inches (six to nine centimeters) long with an eight-inch (20-centimeter) wingspan. The largest bat in the U.S. is the greater mastiff bat. It can grow as long as seven inches or more with a wingspan of 21 to 23 inches (53 to 58 centimeters).

The majority of bats in the United States are insectivores. They hunt at night and eat flying insects such as mosquitoes, beetles, and moths, many of which are considered pests. Bats provide an important ecological service by eating tons of insects. In a single midsummer night, the 20 million Mexican free-tailed bats from Bracken Cave in central Texas eat more than 200 tons of insects.

Not all bats eat insects. Some live on a diet of nectar and fruit. Bats that feed on nectar also serve as pollinators to nighttime blooming plants. To attract these flying mammals, flowering plants have evolved a musty or rotten perfume. The smell is created by sulphur-containing compounds, which are uncommon in most floral aromas, but have been found in the flowers of many plant species that specialize in bat pollination.

Vampire bats do exist, but there are none in the United States. The closest vampire bats are found in Mexico.

Insect-eating bats hunt using a type of natural sonar called echolocation. They emit a high-frequency sound (undetectable to people) that bounces off surrounding objects. When a sound hits an object, or better yet, an insect, it bounces back to the bat's pronounced ears and gives the bat an audible map for the shape, distance, and location of nearby objects. Everything happens so quickly that a bat can make almost instant turns to catch a flying insect. A bat's echolocation system is so advanced and precise that scientists study bats to make sonar equipment for ships.

A bat's nose can be very useful characteristic for identifying a bat species. Some are small and simple, others are shaped like a pig's nose, and some even have noses shaped like leaves.

Credit : The National Wildlife Federation

Picture Credit : Google 

Weighing less than 3 g, the Etruscan shrew is the smallest known mammal on earth. A very high metabolism means that a shrew can eat up to two times its body weight.

It is able to get so much food because its excellent reflexes and highly fibrous muscles help it catch even the fastest of insects.

Etruscan shrews are solitary and territorial animals. They live alone, except during mating periods. They protect their territories by making chirping noises and signs of aggressiveness. Etruscan shrews tend to groom themselves constantly when not eating, and are always moving when awake and not hiding. The hiding periods are short and typically last less than half an hour. Clicking sounds are heard when these animals are moving, which cease when they rest. Etruscan shrews are more active during the night when they make long trips; during the day, they stay near the nest or in a hiding place. When hunting, Etruscan shrews mostly rely on their sense of touch rather than vision, and may even run into their food at night. In cold seasons and during shortages of food, these animals lower their body temperatures down and enter a state of temporary hibernation (torpor) to reduce energy consumption.

Etruscan shrews occur from Europe and North Africa up to Malaysia. They are also found in the Maltese islands, situated in the middle of the Mediterranean sea. These small animals favor warm and damp habitats covered with shrubs, which they use to hide from predators. Areas, where open terrain such as grasslands and scrub meet deciduous forests, are usually inhabited. They can be found at sea level but are usually confined to the foothills and lower belts of mountain ranges. Etruscan shrews colonize riparian thickets along the banks of lakes and rivers, as well as human-cultivated areas (abandoned gardens, orchards, vineyards, olive groves, and edges of fields). They are poorly adapted to digging burrows, so arrange their nests in various natural shelters, crevices, and abandoned burrows of other animals. Etruscan shrews frequent rocks, boulders, stone walls, and ruins, darting quickly in and out between them.

Etruscan shrews are omnivores. They feed mostly on various invertebrates, including insects, larvae, and earthworms, as well as the young of amphibians, lizards, and rodents, and can hunt prey of nearly the same body size as themselves.

Etruscan shrews occur from Europe and North Africa up to Malaysia. They are also found in the Maltese islands, situated in the middle of the Mediterranean sea. These small animals favor warm and damp habitats covered with shrubs, which they use to hide from predators. Areas, where open terrain such as grasslands and scrub meet deciduous forests, are usually inhabited. They can be found at sea level but are usually confined to the foothills and lower belts of mountain ranges. Etruscan shrews colonize riparian thickets along the banks of lakes and rivers, as well as human-cultivated areas (abandoned gardens, orchards, vineyards, olive groves, and edges of fields). They are poorly adapted to digging burrows, so arrange their nests in various natural shelters, crevices, and abandoned burrows of other animals. Etruscan shrews frequent rocks, boulders, stone walls, and ruins, darting quickly in and out between them.

Credit : Anamalia 

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All mammals have fur on their bodies - hair is a form of fur - and they are warm-blooded. This means that they are able to keep their body temperature stable even if there are changes in their environment. Most begin life inside the mother's body and are born as well-formed babies. Mammal babies feed on their mothers' milk until they are old enough to eat solid foods.

Animals belong to the kingdom Animalia while mammals belong to the class Mammalia. Development from a blastula, consumption of organic material, breath oxygen, motility, and sexual reproduction are the characteristic features of animals while the fur-covered body, sweat glands, three ear bones, single lower jaw bone, neocortex, uterus, giving birth to live young, and mammary glands are the characteristic features of mammals. Vertebrata, Protochordata, Echinodermata, Mollusca, Arthropoda, Annelida, Nematoda, Platyhelminthes, Coelenterata, and Porifera are the animal phyla while placentals, marsupials, and monotremes are the three types of mammals. Animals are multicellular eukaryotes, which develop from a blastula. They consume organic materials and breath oxygen. Mammals are the most developed groups of animals whose body is covered with fur. They have mammary glands and they give birth to the live young. The main difference between animals and mammals is the characteristics. 

Similarities Between Animal and Mammal 

• Animal and mammal are two types of higher organisms classified under kingdom Animalia. 
• They are multicellular eukaryotes. 
• Both grow from a hollow cell sphere called blastula. 
• Both consume organic materials. 
• They breath oxygen. 
• They are motile and undergo sexual reproduction. 

Picture Credit : Google 

Mammals are vertebrates – animals that have a backbone. This means that all mammals have a bony skeleton inside their bodies, which gives them a strong frame. They usually have two pairs of limbs, and organs such as a heart, lungs, stomach and intestine. They come in all shapes and sizes and live in a huge variety of places, from the frozen Arctic wasres to the hottest deserts on Earth.

Of all the different types of animals, mammals are the ones that humans can relate most closely to. This is because humans are just one of the many species of mammals. So what are their characteristics? How are they alike and what are their differences?

They Produce Milk

All mammals have mammary glands, which are used to provide milk for their young. Mammary glands are made up of glandular tissue and ducts and develop from the sweat glands. While many have nipples that allow their young to nurse, one family of mammals, known as monotremes, secrete milk through ducts rather than nipples.

In nearly all mammals, the female is the only one who feeds the young. This means that the nipples of the male, while present, are underdeveloped. In a few species of mammals, such as the Bismarck masked flying fox and Dayak fruit bat, both the male and female are capable of producing milk and both will help care for the young.

They Are Warm-Blooded

A warm-blooded animal is better able to regulate its internal temperature, making it more resilient to outside threats. While a cold-blooded reptile requires a certain external temperature to function, warm-blooded mammals can maintain their body temperature through diet and other methods.

They Have a Four-Chambered Heart

One characteristic of mammals that you cannot see is their four-chambered heart. Reptiles and amphibians have three-chambered hearts, while fish have hearts with two chambers. Birds and mammals are the two classifications of vertebrates that have four chambers.

With a four-chambered heart, the body can easily keep the deoxygenated blood heading to the lungs separate from the oxygen-rich blood heading away from the lungs. This means the animal has fully oxygenated blood available at all times. By having constant access to a well-oxygenated supply of blood, mammals are able to physically exert themselves more fully and without the need for frequent breaks.

Most Replace Their Teeth Once Over Their Lifetime

With the exception of a few mammals, such as kangaroos and manatees, mammals replace their teeth once over their lifetime. Born with deciduous teeth, these fall out to make room for the primary teeth. If they lose a primary tooth, it doesn’t grow back. This contrasts with animals such as alligators and sharks, that can replace teeth throughout their life.

Their Lower Jaw is Made of a Single Bone

In other classes of vertebrates, the lower jaw is made up of several bones and is not attached to the skull. The mammal’s jaw is made of a single bone, attached to the skull. This solid structure gives the mammal’s jaw tremendous power.

They are Protected by Hair

All mammals have some form of hair or fur during some period of their life. Some, like dogs and cats, are covered in fur throughout their life. Others, such as dolphins, have a light covering of hair early in development.

Hair can provide camouflage, protection from the weather, and aid in exploring their environment.

Credit : A-Z Animals 

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The largest of all the turtles is the leatherback, which can grow up to 1.6 m long and weigh about 360 kg - almost as heavy as a horse. Unlike other turtles, its shell is not hard but slightly flexible with an almost rubber-like feel. It can stay underwater for over an hour and dive to a depth of about 1280 m.

The leatherback sea turtle is the most unique of all sea turtle species. As the only living member of the family Dermochelyidea, they are the largest living turtle species and have the greatest migratory distribution of any reptile on the planet. Its distinguishing feature is its carapace, which has a smooth, leathery skin that covers a flexible matrix of bone. This carapace is highly specialized for diving to extreme depths of up to 4,000 feet (1,219 meters). In addition, a unique thermoregulatory adaptation allows leatherbacks to maintain core body temperatures at these extremely cold depths.

Adult leatherbacks have few natural predators, but their eggs and newborns are preyed upon by many animals, including birds, raccoons, and crabs. Female leatherbacks tend to return to the same nesting area to lay their eggs. Their large size makes them opportunistic in selecting a nesting beach. Like most reptiles, temperature determines the gender of the offspring—if it’s warm inside the nest, females will be born. Likewise, if temperatures are cooler, males develop. Once the eggs hatch, they’re on their own—the baby sea turtles must make it into the water and learn to fend for themselves without any care from their parents. Leatherbacks reach maturity at approximately 16 years old. Their average lifespan is unknown, but it’s thought to be at least 30 years.

Leatherbacks are found in tropical and temperate marine waters all over the world. They live off both the east and west coasts of the United States, and also in Puerto Rico, the Virgin Islands, and Hawaii. Leatherbacks spend most of their lives at sea and sometimes look for prey in coastal waters.

Jellyfish make up the biggest portion of their diet, but they also eat seaweed, fish, crustaceans, and other marine invertebrates. Leatherbacks have downward-pointing spines in their throat, which allows jellyfish to be swallowed, but prevents them from coming back up.

Credit : The National Wildlife Federation

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The hawksbill gets its name because its mouth resembles the sharp beak of a hawk. The turtle, which has a beautifully coloured and patterned shell, lives among the coral reefs of the Pacific, Indian and Atlantic Oceans. It can grow to about 1.14 m, more than half the length of a full-size bed, and weigh almost 70 kg.

Hawksbill turtles often nest in small numbers, and usually on remote beaches. The largest populations of hawksbills are found in the west Atlantic (Caribbean), Indian, and Indo-Pacific Oceans.

The largest nesting populations of hawksbill turtles occur in Australia and Solomon Islands. Approximately 2,000 hawksbills nest annually on the northwest coast of Australia and 6,000 to 8,000 nest annually in the vicinity of the Great Barrier Reef. The largest rookery for hawksbill turtles in the South Pacific Ocean is in the Arnavon Islands of the Solomon Islands, where approximately 2,000 hawksbill nest each year. Arnavon hawksbills have been heavily exploited for their shell for centuries, but two decades of conservation and monitoring efforts are showing encouraging signs of recovery. Around 2,000 hawksbills nest each year in Indonesia and 1,000 in the Republic of Seychelles. 

In the Atlantic, the greatest number of hawksbill nests are laid in Mexico, Cuba, and Barbados, but nesting occurs throughout the Insular Caribbean. The most significant nesting within the United States occurs in Puerto Rico and the U.S. Virgin Islands. Each year, about 500 to 1,000 hawksbill nests are laid on Mona Island, Puerto Rico and another 100 to 150 nests on Buck Island Reef National Monument off St. Croix. In the continental United States, nesting is rare and is restricted primarily to the southeast coast of Florida and the Florida Keys. 

In the U.S. Pacific, hawksbills nest primarily in Hawaii where 10 to 25 females nest annually on beaches along the south coast of the island of Hawaii and the east coast of the island of Molokai. This population may constitute one of the smallest hawksbill nesting populations in the world, but is the largest in the Central North Pacific Ocean. In the Eastern Pacific, approximately 700 females nest annually from Mexico to Peru.

Credit : National oceanic and atmospheric administration

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This native of South Africa not only closes its hinged shell after pulling its head inside, it also releases a foul smell from its musk glands to keep predators away.

Cool Facts About The Hinged Terrapin

• The Serrated Hinged Terrapin is the largest of the hinged terrapins.  They can grow between 30 and 50cm in length where females are usually larger than males
• Found throughout tropical East Africa, the Serrated Hinged Terrapin is one of the most common hinged terrapin species.
• Not selective about basking locations, the Terrapins lounge mostly on logs and rocks, but they also been found hitching rides on the backs of hippopotamuses!
• Serrated Hinged Terrapins are so named because they have a hinge in their shell that they are able to close after pulling their head and front legs inward.

Hide ‘n’ Seek

Serrated Hinged Terrapins are carnivores that feed on a variety of creatures, including snails, mollusks, insects, frogs, and fish.  They will also consume carrion if available and have been known to eat ticks and parasites off of wallowing water buffalo.  Occasionally, they may also eat fruit. They may look cute and cuddly (for a amphibian) but you need to be careful of their incredibly sharp claws, which come in handing for hunting and defending against predator attacks. Typically they will only use this defensive strategy when hiding in the shell doesn’t seem to be working. These interesting creatures need to be on the lookout for numerous predators. During their lifetime, the Terrapins are preyed upon by crocodiles, monitor lizards, and the mongoose.

Long Walk To Water

Serrated Hinged Terrapins lay their eggs between October and January near water although they can sometimes be as far away as 500m.  The female will deposit between 7 and 25 eggs by burying them as deep into the ground as possible.  Burying the eggs not only protects them from predators but also prevents the eggs from drying out in the sun.   Hatchlings will appear between March and April and grow rapidly.

Stable and Happy

Luckily, with a widespread range and a stable population trend, the Serrated Hinged Terrapins are abundant and not listed as protected by any agency.  Although they are sometimes caught by fisherman and consumed by various peoples, overall, human activity has not harmed the population. It is always nice to hear that a population is doing well, so I always try to share these stories (I just wished it occurred more frequently).

Credit : Google 

Picture Credit : Google 

Female turtles lay their eggs in holes they dig on sandy beaches and then return to the sea. The eggs hatch in about 60 days, usually at night to give the tiny babies the best chance to avoid predators as they scurry down the beach and into the sea.

Sea turtles hatch throughout the year but mostly in summer.

Hatchlings use a carbuncle (temporary egg tooth) to help break open the shell.

After hatching, the young turtles may take 3 to 7 days to dig their way to the surface.

Hatchlings usually wait until night to emerge from the nest. Emerging at night reduces exposure to daytime predators. Studies have shown that some nests will produce hatchlings on more than one night.

For most sea turtle species, undisturbed nests can have more than 90% of the clutch successfully hatch. Nests disturbed by humans or animal predators tend to have a 25% or even much lower success rate.

Reaching the ocean

There are several theories as to how hatchlings find the sea.

• Hatchlings may discriminate light intensities and head for the greater light intensity of the open horizon.
• During the crawl to the sea, the hatchling may set an internal magnetic compass, which it uses for navigation away from the beach.

When a hatchling reaches the surf, it dives into a wave and rides the undertow out to sea.

• A "swim frenzy" of continuous swimming takes place for about 24 to 48 hours after the hatchling enters the water.
• This frantic activity gets the young turtle into deeper water, where it is less vulnerable to predators.
• There have been reports of swimming hatchlings diving straight down when birds and even airplanes appear overhead. This diving behavior may be a behavioral adaptation for avoiding predation by birds. 
• Past the surf zone, hatchlings use their internal magnetic compass for orientation.

The"lost" years.

After entering the ocean, the hatchlings of many species of sea turtles are rarely seen for 1 to 3 years. These are referred to as the “lost years.”

Researchers generally agree that most hatchlings spend their first few years living an oceanic existence before appearing in coastal areas. Although the migratory patterns of the young turtles during the first year has long been a puzzle, most researchers believe that they ride prevailing surface currents, situating themselves in floating seaweed where they are can find food.

Research suggests that flatback hatchlings do not go through an oceanic phase. Evidence shows that the young turtles remain inshore following the initial swim frenzy. Most remain within 15 km (9.3 miles) of land.

Credit : Sea world parks & entertainments 

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The names sea turtle and land turtle are a little bit confused among most of general people, as the scientific means are somewhat different. Therefore, a proper understanding would be beneficial for anyone. Scientifically, the term turtle refers to the marine testudines. Freshwater testudines are known as terrapins, and the land living or the terrestrial testudines are scientifically referred as tortoises. However, according to the commonly used terms or names, all these three types are known as turtles with the adjective of the respective environment. Interestingly, certain types are still known as terrapins or tortoises. Therefore, solving this controversy would take a few steps, and this article would be one such step as it discusses the characteristics and performs a comparison between land and sea turtles. In other words, this article is a brief comparison between turtles and tortoises.

Sea Turtle

Sea turtles or turtles are one of the earliest to live on the Earth, and the fossil evidences suggest that they had inhabited the world at least 210 million years ago. The fascinating thing about them is they have been able to survive until today with a wide diversity that accounts more than 210 extant species including land, freshwater, and sea turtles. However, there are only seven sea turtle species currently inhabit the oceans of the world. They are remarkably well adapted to the oceanic lifestyle with developed flippers do locomotion. Turtles are blessed with the longest lifespan of all the animals on the Earth, which is more than 80 years according to certain references but some state that it could go as high as 180 years. Sea turtles are distributed in all the oceans of the world except in the Arctic and Antarctic regions. They come to the surface for breathing and sometimes for navigation. The most fascinating characteristic of sea turtles is that they come back to the same beach that they were born for eggs laying.

Land Turtle

Land turtles, aka tortoises, are land dwelling reptiles belong to Class: Reptilia in general and to the Oder: Testudines in particular. There are more than 45 extant species currently, but the number is more likely to be increased. Tortoises being testudines, they have a shield covering their body known as the shell. The shell comprises of two types of structures known as the carapace (the top portion) and the plastron (the underside), and these two are interconnected by a bridge. In addition, tortoise has both the endoskeleton and the exoskeleton (shell). Land turtles come in different sizes depending on the species. They are diurnal animals more often than not, but some are crepuscular. However, their active time depends mostly on the ambient temperature of the environment. The majority of the tortoises demonstrate the sexual dimorphism, but the differences between the two sexes vary among species. For example, some species have larger male compared to the female, but certain other species have it in the other way around. Upon breeding, the female tortoise digs nesting burrows and lays one to thirty eggs in a burrow. Then, the eggs incubate in the ground for 60 to 120 days depending on the species. Usually, tortoises are herbivores, but some are omnivores as they feed on worms and insects.

Credit :  Difference between.com

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The spectacled caiman (Caiman crocodilius) gets its name from the bony ridge that lies between its eyes that gives it the appearance of wearing a pair of glasses. The spectacled caiman belongs to the family Alligatoridae along with many other species of crocodile and alligator. Unlike the other species in its family, the caiman seems to have benefited from the removal and displacement of the larger crocodilian species. The spectacled caiman is considered Least Concern by the IUCN and enjoys a range that stretches from southern Mexico all the way to Brazil (as pictured below). They were introduced in Puerto Rico, Cuba, and the United States. The spectacled caiman is considered to be highly adaptable to the rivers and lowland wetlands that it inhabits. These attributes have led to it being one of the most widespread species within its taxonomic family.

The yellow and black spots that distinguish juveniles from adults is a well-known feature of this species and can be observed in the photos below. This species can grow to a mere 8ft compared to its larger cousin, the black Caiman that can grow up to 19 feet in length. The males tend to be larger than the females. Adult spectacled caimans are a dull olive green and the yellow and black spots that juveniles have fade as they age. This species of crocodile endures the extremes of its ecosystem using a form of hibernation called estivation.  Estivation is the ability to hibernate through the dry and low prey summer season in its habitat. When its environment becomes too harsh the spectacled caiman can burrow in the mud and protect itself from overheating.

The caiman is considered a keystone species in its environment because it enjoys the status of a top predator, and its removal can lead to harsh consequences lower in the food chain. As juveniles, spectacled caimans consume aquatic insects, small fish, crustaceans, and mollusks. As adults, they eat just about anything they can catch, including mammals, birds, fish, and other reptiles. They have a total number of 72 to 78 teeth. Males and females become sexually mature around 4-7 years of age but it has been shown that sexual maturity can be based on size and size can be based on competition. In areas of high competition, it may take a particular individual more or less than 4-7 years to completely mature.

Some of the main threats for this species are being hunted for their skin and being killed solely because they frighten local populations. Although they are not currently threatened, their conservation as a keystone species is important because they keep many of their prey species in check in delicate river and lowland areas. In the areas that they have been introduced, specifically Cuba, they have put native populations of other species of crocodile at risk because they can outcompete local species. Also, since the 1950’s when hunting of the several larger species of crocodiles was occurring, the caiman has proliferated because of a lack of competition from larger species with healthier populations. The caiman is a species that in some areas of its range needs to be controlled and maintained in ecosystems where it occurs naturally.

Credit : Stedwards. education

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Gharials are also reptiles in the Crocodylidae family. They live in fresh water, and are only found in parts of India and Nepal. A long, sleek snout that displays rows of very sharp, flesh-tearing teeth, and a bulbous lump on the male's snout make them different from their cousins. Gharials can grow up to six metres in length.

Physical Description

The gharial is one of only two species in the Gavialidae family. It  has a characteristic elongated, narrow snout, similar only to the tomistoma (previously called the false gharial). Many sharp, interlocking teeth line the gharial's elongated jaws.

Gharials exhibit sexual dimorphism — or differences in characteristics between males and females of the same species — in both size and appearance. Adult males develop a bulbous growth at the tip of their snout, called a "ghara" after the Indian pot it resembles. The ghara has several functions. It partially covers the crocodiles nostrils and acts as a vocal resonator, creating a loud, buzzing sound when the gharial vocalizes. It is also a visual signal for females, helping males attract a mate.

Because of their weak leg muscles, gharialsare poorly equipped for locomotion on land. Most of their movement takes place in the water. When they do move across land, gharials push their bodies forward across the ground, a motion known as belly-sliding.

Size

The gharial is one of the largest of all crocodilian species, with males reaching 16 to 20 feet (5 to 6 meters) in length. Females typically grow to lengths of 11.5 to 15 feet (3.5 to 4.5 meters).

Native Habitat

Historically, the gharial's range spanned rivers of Bangladesh, Bhutan, India, Myanmar, Nepal and Pakistan. Today, only fragmented populations remain in Nepan and northern India.

Gharials are adapted to an aquatic lifestyle in large rivers, and individuals typically only leave the water to bask and nest on sandbanks.

Food/Eating Habits

Adult gharials primarily eat fish, while juveniles also feed on insects, crustaceans and frogs. The crocodile's unique snout, along with its sharp, interlocking teeth help it capture prey, quickly striking at fish in the water. At the Smithsonian's National Zoo, gharials eat a variety of fish.

Reproduction and Development

Like other crocodilians, gharials are polygamous, with one male defending a territory where he and several females live. Territorial and courting display behaviors include head slapping the water and buzzing vocalizations. Females reach sexual maturity when they are approximately 9.8 feet (3 meters) in length, and males at about 13 feet (4 meters). Mating typically occurs in December and January.

Females dig a nest during the dry season, between March and April, and deposit an average of 40 eggs, which hatch from 60 to 80 days later. As with all crocodilians, the sex of the hatchlings is determined during incubation.  Females, who are protective of their nest and hatchlings, provide the sole parental care.

Credit : Smithsonian’s national zoo & conservation biology institute 

Picture Credit : Google 

Baby crocs and alligators will catch insects and spiders to eat. As they grow, fish and birds form a larger part of their diet. When fully grown, they will prey on anything that comes their way: fish and birds, as well as small and large mammals.

Wild crocodiles are advantageous carnivores, capable of eating whatever prey that happens to stumble upon them. They have even been known to eat humans from time to time as well, but more on that later!

The larger the crocodile, the larger the prey. According to a study done by the Northern Australia Environmental Resources Hub, saltwater crocodiles have been known to eat large wildebeest and even other crocodiles!

A captive crocodile in a zoo is will often eat:

Mice
Rats
Raw chicken
Raw beef
Fish

Whether it be in captivity or in the wild, crocodiles are highly opportunistic eaters, and they are also comfortable eating dead animals or carcasses.

How Much Does a Crocodile Eat?

A crocodile eats on average 2-5 pounds of meat per day, or roughly 5% of its body weight per week. It depends on the overall size of the crocodile and the amount of food that is readily available to them, however. A croc with a great deal of prey nearby may eat much more than 2 pounds of meat a day!

According to the Journal of Herpetology, an adolescent crocodile needs to eat at least 4% of its body weight weekly depending on its size, while a captive croc needs to eat at least four times that amount.

Crocodiles usually require less food than warm-blooded mammals, but this doesn’t mean they don’t feast or gorge themselves on food. They are one of the few predators incapable of tearing their food into smaller pieces- they have to eat their meals whole.

Crocodiles are also not picky eaters in the least. They will eat most anything that crosses their path or can’t outswim them. Depending on the location of the species and the current weather, crocodiles will eat a variety of different things.

For example, crocs will eat much more fish and aquatic creatures during wet and rainy months, while they will need to eat more land mammals during drier months. No matter what, if a crocodile can fit the unsuspecting prey in its jaws, it will do its best to eat it!

Credit :  A-Z Animals 

Picture Credit : Google 

 

Yes, and they look after them very carefully. Female crocodiles scoop out a pit in the ground then lay 30 or more eggs there, covering them up with earth or sand. The female will stay nearby, guarding the nest for about three months while the eggs become ready to hatch.

Crocodiles stayed within the egg-laying branch of the family along with alligators, caiman, and gharials who all lay hard-shelled eggs. Sexually mature females over the age of 10 years who have reached a certain trigger weight will lay a clutch of eggs into the soft, cool earth and build up a shallow mound on top of it.

Their eggs are very dependent on the temperature of the ground and so different crocodiles lay their eggs at different times and different places depending on this as a key factor. Unlike birds, crocodile eggs are born unsexed – the sex of the young isn’t predetermined by their chromosomes. It is the temperature that determines whether they grow up male or female. Mother crocs will sometimes build up or shallow out a nest if the temperature varies too much from ideal. It is a delicate business in the wild – but a very useful tool for captive-bred individuals.

How Many Eggs Does A Crocodile Lay?

The crocodiles go for the ‘more is best’ approach to young – laying up to 60+ eggs in one clutch. Some larger/older crocodiles can lay many more and younger/smaller females often many less. Regardless of the number, the nest-building process remains the same – with the same digging technique and locations. All the eggs are hard-shelled although they are translucent when first laid, only becoming solid white just before hatching.

Crocodile eggs are about the same size as a large chicken egg but are a different shape. Reptile eggs don’t have one end larger than the other and are certainly not pointed at the end. They are more capsule-like and symmetrical at each end. They are also considerably heavier at around 85g (3oz) – where a large chicken egg only weighs around 57g (2oz).

Where Do Crocodiles Lay Their Eggs?

If you were thinking of going out and finding yourself a haul of crocodile eggs for a feast – the American Alligator is listed as ‘threatened’ by the IUCN – so poaching their eggs without the right permit will be illegal, unethical, and also highly dangerous.

They tend to lay their eggs in March or April and the soft sedimentary or clay soils are easy for mum to dig. A large flat area of earth found in an otherwise leaf and twig-covered woodland area is almost certainly a crocodile nest – but take care – mum is always close by. Predation of crocodile eggs is quite common – with the raccoon being the most likely thief. Other predators might be bears, birds and even other reptiles – so mum is usually watching out for any disturbance.

She has to listen out for the young to start chirping just before they hatch – so if she can hear a newborn crocodile that is buried underground – she will certainly hear you!

Picture Credit : Google