Explain the general characters of phylum Mollusca. Give one example of following classes of Mollusca; (i) Gastropoda; (ii) Pelecypoda; (iii) Cephalopoda.
Explain the general characters of phylum Mollusca. Give one example of following classes of Mollusca; (i) Gastropoda; (ii) Pelecypoda; (iii) Cephalopoda.
Characteristics of Mollusca:
(i) Body is soft, bilaterally symmetrical, with little segmentation and without appendages. The size of body varies from a microscopic to a giant form such as Octopus of upto 50 feet.
(ii) Body cavity is haemocoel. True coelom is reduced and restricted to the pericardial cavity am the lumen of gonads and nephridia.
(iii) Digestive tract has a simple structure.
(iv) Sexes are usually separate.
(v) Respiration through gills, mantle or a "lung" of the mantle.
(vi) Circulatory system is open except in cephalopods.
(vii) Excretion by a pair of metanephridia or kidneys.
Classes and their examples:
(i) Gastropoda: Pila (apple snail)
(ii) Pelecypoda: Unio (fresh water mussel)
(iii) Cephalopoda: Loligo (squid)
Characteristics of Mollusca:
(i) Body is soft, bilaterally symmetrical, with little segmentation and without appendages. The size of body varies from a microscopic to a giant form such as Octopus of upto 50 feet.
(ii) Body cavity is haemocoel. True coelom is reduced and restricted to the pericardial cavity am the lumen of gonads and nephridia.
(iii) Digestive tract has a simple structure.
(iv) Sexes are usually separate.
(v) Respiration through gills, mantle or a "lung" of the mantle.
(vi) Circulatory system is open except in cephalopods.
(vii) Excretion by a pair of metanephridia or kidneys.
Classes and their examples:
(i) Gastropoda: Pila (apple snail)
(ii) Pelecypoda: Unio (fresh water mussel)
(iii) Cephalopoda: Loligo (squid)
