Fish -- Animals
Evolutionary Milestones
Fish are the first animal to have a hollow nerve tube and a backbone.
Habitat
Fish live in the water.
Anatomical/Structural Features
Fish have scales, a closed circulatory system with a two-chambered heart, a complex brain and sense organs, and an efficient respiratory system. Most have paired fins, gills, and scales.
Chondrichthyes have a skeleton completely composed on cartilage, a lateral line system, and a jaw.
Osteichthyes have a skeleton of bone, a backbone composed of vertebrae (separate hard segments), a lateral line system, and a swim bladder.
Agnatha have no jaw, no fins, and no scales.
Symmetry
Fish have bilateral symmetry.
How They Acquire Nutrients
Fish are heterotrophs, and can be predators, carnivores, herbivores, or parasites.
What They Eat
Fish can eat other fish, plankton, algae, crustaceans, parasites, snails, oysters, mussels, clams, shrimps and crabs.
What Eats Them
Birds, bears, reptiles, other fish, and people often eat fish.
Mobility
Most fish have paired fins that aid in swimming. Some have pectoral fins that flap up and down. Other fish nave no fins and move in a snake-like pattern.
Reproduction
Fish reproduce sexually; most use external fertilization, but few use internal fertilization. Fish have different sexes.
Development
Eggs are "born alive".
Examples
Some examples of fish include hagfish, sharks, rays, goldfish, minnows, catfish, salmon, bass, and tuna.
Other Information
Fish are separated into three classes: chondrichthyes, osteichthyes, and agnatha.
Fish are the first animal to have a hollow nerve tube and a backbone.
Habitat
Fish live in the water.
Anatomical/Structural Features
Fish have scales, a closed circulatory system with a two-chambered heart, a complex brain and sense organs, and an efficient respiratory system. Most have paired fins, gills, and scales.
Chondrichthyes have a skeleton completely composed on cartilage, a lateral line system, and a jaw.
Osteichthyes have a skeleton of bone, a backbone composed of vertebrae (separate hard segments), a lateral line system, and a swim bladder.
Agnatha have no jaw, no fins, and no scales.
Symmetry
Fish have bilateral symmetry.
How They Acquire Nutrients
Fish are heterotrophs, and can be predators, carnivores, herbivores, or parasites.
What They Eat
Fish can eat other fish, plankton, algae, crustaceans, parasites, snails, oysters, mussels, clams, shrimps and crabs.
What Eats Them
Birds, bears, reptiles, other fish, and people often eat fish.
Mobility
Most fish have paired fins that aid in swimming. Some have pectoral fins that flap up and down. Other fish nave no fins and move in a snake-like pattern.
Reproduction
Fish reproduce sexually; most use external fertilization, but few use internal fertilization. Fish have different sexes.
Development
Eggs are "born alive".
Examples
Some examples of fish include hagfish, sharks, rays, goldfish, minnows, catfish, salmon, bass, and tuna.
Other Information
Fish are separated into three classes: chondrichthyes, osteichthyes, and agnatha.