All Species Are Aquatic In Which Of The Following Animal Groups?

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sea turtle (reptile). Green turtle (Chelonia mydas) (C. mydas) off the Hawaii Islands, Pacific Islands. Green sea turtle, chelonian. Homepage blog 2011, science and technology, animal — © iStockphoto/Thinkstock

How many of you think the Brady Bunch episode in which Peter was studying for a biological science examination? He asked Marcia for help, and she taught him the mnemonic: "A vertebrate has a dorsum that'southward straight." Well, not all vertebrates take straight backs, but all have backbones, or vertebral columns, that help support their bodies.

Although the vertebral column is possibly the near obvious feature in vertebrates, it was not present in the first ones, which probably had only a notochord (flexible rodlike structure which plays a role in the development of the nervous system). The vertebrate has a singled-out caput, with a differentiated brain and three pairs of sense organs (nasal, optic, and otic [hearing]). The body is divided into torso and tail regions.

Several groups of vertebrates inhabit planet Earth. Let's accept a tour of the five main vertebrate groups alive today: the fishes, amphibians, reptiles, birds, and mammals.

Fishes

whale shark
A whale shark (Rhincodon typus) and a snorkeler off the declension of Australia.
© Comstock Images/Jupiterimages

The get-go fishes are thought to have emerged some 518 meg years ago during the Cambrian Period of World'southward history. Today, in that location more than 30,000 species of fishes found in the fresh and common salt waters of the world. Living species range from the archaic, jawless lampreys and hagfishes through the cartilaginous sharks, skates, and rays to the abundant and diverse bony fishes.

Fishes range in adult length from less than 10 mm (0.4 inch) to more than xx meters (60 anxiety) and in weight from nearly 1.v grams (less than 0.06 ounce) to many thousands of kilograms. Some alive in shallow thermal springs at temperatures slightly higher up 42 °C (100 °F), others in common cold Arctic seas a few degrees below 0 °C (32 °F) or in cold deep waters more than than 4,000 meters (13,100 anxiety) beneath the ocean surface.

Fish reproduction methods vary, but most fishes lay a large number of small eggs that are fertilized and scattered outside of the body. The eggs of pelagic (open ocean) fishes usually remain suspended in the open water, while many shore and freshwater fishes lay eggs on the bottom or among plants. The mortality of the young and especially of the eggs is very loftier, and oft only a few individuals grow to maturity out of hundreds, thousands, and in some cases millions of eggs laid.
Amphibians

ruddy salamander (Pseudotriton ruber)
Red salamanders (Pseudotriton ruber) are found in the eastern The states.
© Liz Weber/Shutterstock.com

Amphibians evolved from fully aquatic tetrapods—(which were essentially "limbed fish") who descended from lobe-finned fish—sometime between the Early Devonian Period (which began 419 million years ago) to the Early on Pennsylvanian Subperiod (which began 323 million years ago). The name amphibian, derived from the Greek amphibious significant "living a double life," reflects this dual life strategy—though some species are permanent land dwellers, while other species have a completely aquatic mode of existence.

In that location are three living groups of amphibians (caecilians, salamanders, and anurans [frogs and toads]) that, collectively, make up more than 7,300 amphibian species. 1 similar tendency among amphibians has been the evolution of straight development, in which the aquatic egg and complimentary-pond larval stages are eliminated. Evolution occurs fully within the egg capsule, and juveniles hatch as miniatures of the developed body form. Virtually species of lungless salamanders (family Plethodontidae), the largest salamander family, some caecilians, and many species of anurans have direct development. In addition, numerous caecilians and a few species of anurans and salamanders give nascence to live immature.

Frogs and toads display a broad variety of life histories. Some eolith eggs on vegetation above streams or ponds; upon hatching, the tadpoles drib into the water where they continue to develop throughout their larval phase. Some species create cream nests for their eggs in aquatic (watery), terrestrial (state-based), or arboreal (tree-based) habitats; after hatching, tadpoles normally develop in water. Other species deposit their eggs on land and transport them to water, while marsupial frogs are so called because they bear their eggs in a pouch on their backs. A few species lack a pouch and the tadpoles are exposed on the dorsum; in some species, the female deposits her tadpoles in a pond as shortly as they sally from eggs.
Reptiles

male flying lizardPremaphotos/Nature Picture Library

Reptiles are air-animate vertebrates. They accept internal fertilization, amniotic evolution (in which the embryo develops within a set of protective extra-embryonic membranes—the amnion, chorion, and allantois), and epidermal scales covering part or all of their body. The major groups of living reptiles—the turtles, tuataras, lizards and snakes, and crocodiles account for over eight,700 species.
Reptiles evolved from amphibians during the kickoff role of the Pennsylvanian subperiod (323 one thousand thousand to 299 million years ago) and retained many amphibian structural characteristics. While most reptiles feed on other organisms, a few are herbivorous (e.g., tortoises). As cold-blooded animals, reptiles tend to be limited to temperate and tropical areas, but, where they occur, they are relatively mutual; however, they are non as big or conspicuous as birds and mammals. Nearly reptiles are terrestrial, but a few are aquatic. They motility about by creeping or pond in a way similar to amphibians. Some reptiles, all the same, can lift the body from the basis and run apace either in a quadrupedal or bipedal fashion. Reptiles lay relatively large, shelled eggs. In a few instances, the eggs and young are cared for by the female; in others, the immature are born alive.
Birds

European white pelican
European white pelicans (Pelecanus onocrotalus) in flight.
© Digital Vision/Getty Images

Birds make up any of the 9,600 living species unique in having feathers, the major characteristic that distinguishes them from all other animals. They are warm-blooded vertebrates more than related to reptiles than to mammals. They have a four-chambered center (every bit exercise mammals), forelimbs modified into wings (a trait shared with bats), a hard-shelled egg, and swell vision. Their sense of smell is not highly developed, and their auditory range is limited.

Although virtually are capable of flight, others are sedentary, and some are flightless. In a way similar to their relatively shut relatives the reptiles, birds lay shelled eggs. The immature are usually cared for in a nest until they are capable of flight and cocky-feeding, only some birds hatch in a well-adult state that allows them to begin feeding immediately or even have flying. (Nesting activities similar to those of some birds are seen in the crocodilians.)

The origin of birds, feathers, and avian flight accept long been hotly debated; the evolution of birds from reptilian ancestors is universally accepted, yet. The diversity of theropod dinosaurs (a various group of cannibal "lizard-hipped" dinosaurs), some with feathers, has greatly expanded our perspective of the evolution and early diversification of birds. While it is known that the critical catamenia in avian evolution and flight took place during the Early Cretaceous (145.five 1000000 to 99.6 million years ago), in that location is show that feathers on theropods emerged much earlier, possibly during the Triassic and Jurassic Periods (some 252 million to 145 million years ago).
Mammals

Okapi (Okapia johnstoni).
© IMPALASTOCK/iStock/Getty Images Plus

There are approximately 5,000 species of mammals living today. Mammals differ from other vertebrate animals in that their young are nourished with milk from special mammary glands of the mother. Mammals are distinguished past several other unique features. Hair is a typical mammalian feature, although in many whales it has disappeared except in the fetal stage. The mammalian lower jaw is hinged directly to the skull, instead of through a carve up bone (the quadrate) as in all other vertebrates. A concatenation of 3 tiny bones transmits sound waves across the eye ear. A muscular diaphragm separates the heart and the lungs from the abdominal crenel. Mature blood-red blood cells (erythrocytes) in all mammals lack a nucleus; all other vertebrates take nucleated carmine blood cells. The oldest known animals classified as mammals evolved near the boundary of the Triassic and Jurassic Periods, some 200 1000000 years agone.

This group of vertebrates ranges in size from tiny shrews or pocket-size bats weighing only a few grams to the largest known animals, the whales. Most mammals are terrestrial, feeding on both animal and vegetable matter, but a few are partially aquatic or entirely so, every bit in the case of the whales or porpoises. Mammals motility almost in a peachy variety of ways: burrowing, bipedal or tetrapedal (4-legged) running, flight, or swimming. Reproduction usually involves the immature developing within the uterus, where nutritive materials are fabricated available through an allantoic placenta or, in a few cases, a yolk sac. In placental mammals, young accept a longer developmental menses inside the uterus. In marsupials, the relatively undeveloped young are carried in a pouch, where they attach themselves to their mother's nipple until they get fully adult. Monotreme mammals (that is, the platypus and echidna) differ from other mammals in that they lay eggs which hatch.