Distribution :- Unio is commonly found in India, Europe, Atlantic Slope and U.S.A.
Habit and Habitat:- Unio is found at bottom in ponds, lakes, streams and rivers buried in the sand or mud.
1) Unio is commonly known as freshwater mussel.
2) Body is Soft, unsegmented bilaterally symmetrical and flattened, measuring about 5-10 cm in length and enclosed in a calcareous shell.
3) Shell consists of two separate equal pieces or values on the right and left sides of the body.
4) Foot is large, muscular and wedge-shaped used for burrowing.
5) Sexes separate but the male and female shells are alike.
6) Development includes glochidium larva.
7) Two bipectinate gills ,one on each side of the visceral mass, are present.
It is used for dissection purposes; its shell is used to make buttons, tools, jewelry etc.
Distribution:- Octopus is cosmopolitan in distribution. It is commonly found in Europe and India. Atlantic and pacific Coasts, Alaska to lower california and cape cod.
Habit and Habitat:- Octopus is a marine, bottom dwelling nocturnal Cephalopod spending daylight hours in rocky crevices, shady under-water caverns and in coral reefs.
1) Octopus is popularly known as devil-Fish.
2) Body is globose and bag- like the head and trunk region.
3) Head bears a pair of eyes and eight elongated equal arms webbed at the base which surround the mouth.
4) Shell is absent.
5) Mantle enclosed the mantle cavity and the visceral mass.
6) Octopus produces inky-fluid which diffuses in water and forms a smoky screen for defense from the enemies.
They have been used to study blood pigments, immune mechanisms, neurotransmitters and hormonal control of reproduction and aging, they are also known as Octopus.