Wednesday, September 2, 2020

Animal Kingdom : Vertebrates : FISH

 Animal Kingdom : Vertebrates :

Vertebrates A typical fish’s skeleton consists of the spine, skull and jaws, ribs, and fin supports


We will now turn to chordata phylum.

The chordates are animals that have either a backbone or a pliable rod running the length of the body. They include all the vertebrates, and also the aquatic tunicates (sea squirts and salps) and lancelets.

FISH : there are 3 types of fishes,


As their name indicates, the jawless fish do not have hinged jaws. The group consists of fewer than 40 species of eel like lampreys, and may also include the slimy hagfish.


With some 32,000 species, the bony fish make up most of the fish on the planet. Nearly all of them are ray finned fish (with fins supported by bony struts or spines), but they also include lobe-finned fish related to the ancestors of all land vertebrates.


The sharks, rays, and their relatives have skeletons made from gristly, pliable cartilage instead of bone. There are about 1,200 species, which include the largest,  most powerful fish in the sea.


This group is made up of the lampreys, and may also include their distant relations the hagfish.


Petromyzon marinus

Location: N. Atlantic, N. America, Europe

Length: Up to 4 ft (1.2 m)

Diet: Fish blood

Although it looks like an eel, this is a completely different kind of animal, descended from the jawless fish that lived in the oceans of the distant past.

Instead of jaws it has a sucker armed with sharp teeth, used to attack other animals. The lampreys are often seen as primitive because they retain many features seen in fish that lived in the Devonian Period 400 million years ago, But the sea lamprey has evolved into a highly specialized parasite of other fish.

Latching on with its toothed sucker, a lamprey uses its teeth and sharp tongue to cut a hole in the victim’s skin, so it can suck blood. Adult sea lampreys feed at sea, but they swim up rivers to breed and spend their early lives in freshwater.

(Do you know, The wormlike larval stage of a sea lamprey can live for up to 17 years buried in a river or lake bed.)

A lamprey’s skull and skeleton are made of pliable cartilage, like those of a shark, but unlike a shark the lamprey does not have a hinged jaw. 

The mouth is surrounded by a disk of tough, flexible tissue studded with teeth made of keratin, the substance that forms our fingernails. The mouth and respiratory tube are separate, so the lamprey can draw water over its gills while its mouth is clamped to a victim.

A single nostril on top of the lampreys head draws water into an olfactory sac lined with tissue that detects the scent of possible prey. The olfactory sac is bigger than the lampreys brain. When a fish is attacked by a sea lamprey, it has few defenses. The lamprey clings tightly with its sucker, and is not easy to dislodge. As it bores into its victim’s flesh, its saliva stops the blood clotting, so the lamprey can drink its fill. Its prey will be lucky to survive the attack.


The seas, lakes, and rivers of the world are home to a dazzling diversity of bony fish, adapted for a wide variety of aquatic habitats and lifestyles.

Most bony fish belong to the ray-finned group, with fins supported by slender bony struts and spines. But a few the coelacanths and lungfish have two pairs of fleshy lobed fins on the lower body containing strong bones. Similar lobe finned fish were the ancestors of all four-legged vertebrate animals.


Pygocentrus nattereri

Location: South America

Length: Up to 13 in (33 cm)

Diet: Mainly small animals and plants

Notorious for the way it can use its razor-sharp teeth to strip its prey to the bone within minutes, the piranha is the most feared of all freshwater fish.

In reality it is mainly a scavenger, feeding on dead and dying animals, small fish, and invertebrates, but there is no doubt about the terrifying efficiency of its feeding technique.

Red-bellied piranhas live in the lowland rivers of tropical South America, where they often swim in shoals. When they find a meal they all start feeding at once, slicing off mouthfuls of flesh, and soon reduce their prey to a bare skeleton. On rare occasions they have done the same to human victims.

(Do you know, A shoal of piranhas was once seen to strip an 88-lb (40-kg) capybara to bare bones in less than a minute.)

Large eyes help the piranha see in the underwater gloom of a tropical forest river to target prey and avoid tangled tree roots. But when the water is cloudy with mud the fish relies on its ability to detect pressure changes in the water, and on its acute sense of smell to find its way.

The piranhas pointed, razor edged teeth interlock perfectly for efficient meat-slicing. Immensely strong jaw muscles enable the fish to scissor flesh away from bones at phenomenal speed.

When piranhas start attacking their prey, the billowing blood in the water attracts even more piranhas, and sends the shoal into a feeding frenzy. The fish crowd together to grab a share of the feast, and may even kill and eat each other in their excitement.


Sharks have a fearsome reputation, but they are not all powerful predators like the notorious great white.

Many prey on fish, and the very biggest sharks eat only tiny marine animals. Most rays feed on shellfish on the seabed. The sharks and rays are cartilaginous fish, with skeletons made of gristly cartilage instead of bone.

Cartilage is  pliable, and usually not strong enough to support a large animal’s body, but this is not a problem for a shark or ray because its body is supported by the water. This allows some species to grow to a colossal size.


Carcharodon carcharias

Location: All warm oceans

Length: Up to 24 ft (7.2 m)

Diet: Fish, seals, and cetaceans

Notorious as the most deadly of all sharks, the great white is specialized for hunting big, warm-blooded animals such as seals, dolphins, and even whales.

Few creatures have such a murderous reputation as the great white shark. Hugely powerful and fast, it is equipped with a devastatingly efficient array of senses for detecting its prey, and a set of ripsaw teeth that can slice its victims in half with a single bite.

Capable of killing and eating almost anything it runs into—including people—its only enemies are orcas and human hunters.

(Do you know, The great white shark's nostrils can sniff out blood in the water from well over 1⁄2 mile (1 km) away.)

Small pores in the shark’s nose contain electrical sensors called ampullae of Lorenzini. At close range these can detect the tiny electrical signals generated by an animal’s muscles, so the shark can pinpoint prey in total darkness.

Each tooth is a serrated blade, like a saw-edged razor, for slicing through skin, flesh, and even bone. A young great white shark has narrower, pointed teeth for seizing slippery fish, but as the shark gets older its teeth become more triangular in shape.

The great white shark never has to worry about losing its teeth, however old it gets. As with all sharks, teeth are shed and continuously replaced, with new teeth moving up from behind. The new teeth roll out from inside the jaws as if on a conveyor belt, while the old, blunt teeth drop off the outside.

That's all about Vertebrates (FISH) .

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Myself Kartik Raising and I completed my bachelor in zoology from KBC NMU, Jalgaon Maharashtra India 425209