Fish Facts
- Fishes are cold-blooded and they can't control their body temperature.
- Fish can feel pain. They have a good sense of taste, sight and touch. Many fish taste without opening their mouth.
- Whale shark is the largest fish and they can grow to 50 feet long.
- Fish like Trigger fish can swim backwards.
- If gold fish is kept in a dark room it will lose its color.
Characteristic of fish
Fish are aquatic vertebrates that have vertebral column called spine. A classic fish is a torpedo shaped. The fish contains head containing a brain and sensory organs, a trunk with a muscular wall surrounding a cavity with the internal organs and a muscular post-anal tail. The following are the general characteristic that all the fish species posses:
General characteristic:
- Ectothermic
- Lateral line
- Two chambered heart
- Gills used for respiration
- No external ears
- No eye lids
All the species of the fish found in the world are classified into the following three groups. They are:
- Agnatha - jawless fish
- Chrondrichthyes - cartilaginous fish
- Osteichthyes - bony fish
- Ray finned group
- Lobe finned group
Each type of fish has its own characteristic based on the group they belong. So it is easy to study the characteristic of a fish based on their group.
Agnatha class:
- Jaws are absent
- Fins are absent
- Skeleton is made up of cartilage
- Posses round eel like body
- Absence of swim bladder and gill covers
- Soft skins made up of scales
- Oviparous animals
- Found in marine and fresh water
Chondrichthyes class:
- Cartilage make up the skeleton
- Body is covered with triangular placoid scales
- Posses ventral subterminal mouth
- Fins are stiff and non-flexible
- Absence of swim bladder
- Internal fertilization
- Found only in marine water
Osteichthyes class:
- Bones make up the skeleton
- The gills are covered with operculum
- Swim bladder is present
- Fins are made up of rays and spines
- This species posses different types of scales
- External fertilization
