Which Animal Is An Ectotherm? Turtle Whale Eagle Kangaroo Description

The subphylum Vertebrata includes all of the familiar large animals and some rare and unusual ones too.  The 7 living classes of vertebrates are distinguished generally on the basis of their skeletal organization, general environmental adaptation, and reproductive system.

subphylum:	Vertebrata
grade:	Agnatha	Chondrichthyes	Osteichthyes	Amphibia	Reptilia	Aves	Mammalia

Iii of the vertebrate classes are fish.   The virtually primitive of these is Agnatha .  Information technology consists of jawless fish that do non take scales.  These are the lampreys and hagfish.  Fish that have skeletons consisting of difficult rubber-like cartilage rather than bone are members of the class Chondrichthyes .  These are the sharks and rays.  All of the bony fish are members of the form Osteichthyes .  Tuna, bass, salmon, and trout are examples of Osteichthyes.

Ray (class Chondrichthyes) and bony fish (class Osteichthyes)

Animals in the course Amphibia spend office of their lives under water and function on country.  Frogs, toads, and salamanders are amphibians.  Many of these species must keep their skin moist by periodically returning to wet areas.  All of them must return to water in social club to reproduce because their eggs would dry out otherwise.  They start life with gills, like fish, and later develop lungs to exhale air.

Salamander and frog (grade Amphibia)

The grade Reptilia includes turtles, snakes, lizards, alligators, and other large reptiles.  All of them accept lungs to breathe on land and peel that does non need to exist kept wet.  They produce an amniote egg which usually has a calcium carbonate rich, leather difficult beat that protects the embryo from drying out.  This is an reward over fish and amphibians because the amniote egg can exist laid on land where information technology is usually safer from predators than information technology would be in lakes, rivers, and oceans.

The class Aves includes all the birds.  They likewise produce amniote eggs merely normally give them greater protection from predators by laying them high off of the ground or in other relatively inaccessible locations.  In the instance of both reptiles and birds, the eggs are fertilized within the reproductive tract of females.  At that place are other striking similarities between reptiles and birds in their anatomies and reproductive systems.  This is not surprising considering birds are descendents of theropod dinosaurs (ii-legged by and large carnivorous dinosaurs).

Birds (course Aves)

Dogs, cats, bears, humans and most other large animals today are members of the vertebrate form Mammalia .  All mammals conceive their immature within the reproductive tract of the mother and, after birth, attend them with milk produced past their mammary glands .  Mammals are heterodonts with potent jaws.  That is to say, they have a variety of specialized teeth (incisors, canines, premolars, and molars).  This allows them to chew their food into minor pieces before swallowing it.  Later, they can swallow whatsoever size establish or animal.  Many reptiles must eat their prey whole, which limits them to hunting smaller game.

Mammalian heterodontism

Similar birds, mammals are endothermic , or warm blooded.  They are able to maintain a relatively constant torso temperature regardless of external environmental conditions mainly by using internal physiological mechanisms. In other words, they are homeothermic , or stable in core torso temperature, as a upshot of endothermy. All of the living species of insects, fish, reptiles, and amphibians are ectothermic , or cold blooded.  They keep their body temperature in a normal range mainly by avoiding exposure to environmental temperature extremes. For example, reptiles usually remain in shaded areas on hot days to prevent fatal overheating.  On common cold nights, their lowered body temperature tin crusade them to become sluggish and inactive.  In contrast, endothermic animals are able to remain active at nighttime and oft in the wintertime when the air temperatures are especially cold.  They can besides motility about in the heat of very warm days.  This ability nigh likely provided an advantage for the early small mammals in surviving alongside dinosaurs and other large reptiles, which plain were generally ectothermic.  The downside of endothermy is the need to swallow far more than calories relative to body size in order to maintain a constant core body temperature.  Small mammals, such as moles with their rapid metabolism rates, must swallow insects or other high calorie foods every one-half 60 minutes or so in lodge to stay alive.  By comparison, cold blooded rattlesnakes usually eat only once every iii-vi weeks and have been known to go without nutrient for as long as two years.

Aiding in mammal body temperature control is their insulating pilus and sweat glands.  Sweating helps to dissipate estrus by evaporative cooling.  Compared to nigh other land mammals, humans are relatively hairless, simply they have far more sweat glands.  Mammals take 4 chambered hearts (like birds), circuitous nervous systems, and large brains relative to the size of their bodies.  This broad range of useful features has made mammals highly adaptive and successful.  They first appeared about 200,000,000 years ago, early in the historic period of dinosaurs, and replaced reptiles equally the dominant class of state animals later on 65,000,000 years agone.  As the rapidly changing environment at that fourth dimension led to the mass extinction of most large reptiles, it left vast evolutionary possibilities which mammals took reward of by rapidly diversifying through adaptive radiations.

Important to mammalian success is their reproductive system.  Their bodies took the amniote egg revolution of reptiles and birds one step further.  In effect, the uterus functions as the protective eggshell.  Young mammals spend a long catamenia of their early evolution within their mother'southward uterus.  Afterward nativity, they are provided with protein and fatty rich milk to swallow and are usually protected until maturity.  Pregnancy and milk production require mothers to significantly increase their ain calorie consumption in order to provide nutrients for their infants.  A nursing human being female ordinarily uses near thirty% of her body'due south energy only to produce milk.

Mammalian mother and her baby

Despite their success, mammals notwithstanding only make upwardly well-nigh .4% of known animal species.  It is humbling to realize that all chordates together are only just over 3.7% of known brute species.  By comparison, well over 1/2 of all animal species are insects.

Copyright � 1998-xx12 past Dennis O'Neil. All rights reserved.
illustration credits

Source: https://www2.palomar.edu/anthro/animal/animal_4.htm

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