2 Fish Anatomy

148 Pages·2011·7.95 MB·English

Revised Edition: 2016
ISBN 978-1-283-49304-8
© All rights reserved.
Published by:
Research World
48 West 48 Street, Suite 1116,
New York, NY 10036, United States
Email: [email protected]
Table of Contents

Chapter 1 - Diversity of Fish

Chapter 2 - Fish Anatomy

Chapter 3 - Decline in Amphibian Populations

Chapter 4 - Evolution of Birds
Chapter 5 - Bird Anatomy
Chapter 6 - Evolution of Reptiles
Chapter 7 - Evolution of Mammals
WT
Chapter 8 - Primate Cognition
Chapter 9 - Animal Testing on Non-Human Primates

________________________WORLD TECHNOLOGIES________________________
Chapter- 1
Diversity of Fish

WT

Fish come in many shapes and sizes. This is a sea dragon, a close relative of the seahorse.
They are camouflaged to look like floating seaweed.
Fish are very diverse and are categorized in many ways. Although most fish species have
probably been discovered and described, about 250 new ones are still discovered every
year. According to FishBase, 31,500 species of fish had been described by January 2010.
That is more than the combined total of all other vertebrates: mammals, amphibians,
reptiles and birds.
________________________WORLD TECHNOLOGIES________________________
By species
Fish systematics is the formal description and organisation of fish taxa into systems. It is
complex and still evolving. Controversies over "arcane, but important, details of
classification are still quietly raging."
The term "fish" describes any non-tetrapod chordate, (i.e., an animal with a backbone),
that has gills throughout life and has limbs, if any, in the shape of fins. Unlike groupings
such as birds or mammals, fish are not a single clade but a paraphyletic collection of taxa,
including jawless, cartilaginous and skeletal types.
Jawless fish
Jawless fish are the most primitive fish. There is current debate over whether these are
really fish at all. They have no jaw, no scales, no paired fins, and no bony skeleton. Their
skin is smooth and soft to the touch, and they are very flexible. Instead of a jaw, they
possess an oral sucker. They use this to fasten on to other fish, and then use their rasp-
like teeth to grind through their host's skin into the viscera. Jawless fish inhabit both fresh
and salt wateWr environments. Some are anadromousT, moving between both fresh and salt
water habitats.
Extant jawless fish are either lamprey or hagfish. Juvenile lamprey feed by sucking up
mud containing micro-organisms and organic debris. The lamprey has well developed
eyes, while the hagfish has only primitive eyespots. The hagfish coats itself and carcasses
it finds with noxious slime to deter predators, and periodically ties itself into a knot to
scrape the slime off. It is the only invertebrate fish and the only animal which has a skull
but no vertebral column. It has four hearts, two brains, and a paddle-like tail.
________________________WORLD TECHNOLOGIES________________________
WT

Lampreys attached to a lake trout

________________________WORLD TECHNOLOGIES________________________
WT

Mouth of a sea lamprey

Pacific hagfish resting on bottom at 280 m

________________________WORLD TECHNOLOGIES________________________
WT

Stir-fried hagfish, from Korean cuisine
Cartilaginous fish
Cartilaginous fish have a cartilaginous skeleton. However, their ancestors were bony
animals, and were the first fish to develop paired fins. Cartilaginous fish don't have swim
bladders. Their skin is covered in denticles, that are as rough as sandpaper. Because
cartilaginous fish do not have bone marrow, the spleen and special tissue around the
gonads produces red blood cells. Some cartilaginous fishes possess an organ called
Leydig's Organ which also produces red blood cells.
There are over 980 species of cartilaginous fish. They include sharks, rays and chimaera.

Tiger shark
________________________WORLD TECHNOLOGIES________________________
WT

Whale shark

________________________WORLD TECHNOLOGIES________________________
WT

Stingray

This elephant fish is a chimaera
________________________WORLD TECHNOLOGIES________________________