WEEK2.
TOPIC: CLASSIFICATION OF FISHES
Fishes can be classified into two main groups:
(a) Classification based on fish habitat:
under this classification, two groups exists:
(i) Fresh water fishes: These fishes live in fresh water, i.e., the water does not contain salts. Examples of such fresh water include pond, streams, rivers and lakes. Examples of fishes in this group include tilapia, carp, perch, trout, mudfish etc.
(ii) Salt water fish: These fishes live in water containing salts such as lagoons, seas and oceans. Examples of salt water fishes include salmons, mackerel, shark, tilapia, rays, eels, etc.
(b) Classification based on body structure: under this classification, two groups also exist:
(i) Bony fishes: These fishes possess bony skeletons. Examples include tilapia, mudfish, carps, trout, catfish, salmon, perch, and herring. Majority of these fishes are found in fresh water.
(ii) Cartilaginous fishes: These fishes possess soft bones composed of cartilages. Majority of these fishes are found in salt water and examples include shark, dolphin, dogfish, rays.
Classification based on nature of body covering:
- Scaly fish: these are fishes that have scales on their body e.g tilapia ,croacker e.t.c
- Non- scaly fish: these are fishes that have no scales on their body. E.g mackerels, catfish, mudfish e.t.c
EVALUATION
- Mention two classification of fishes based on habitat
- Mention two classification of fishes based on body form
ASSIGNMENT: Mention and give examples of classes of fishes based on nature of body cover