Question

Characteristic Features of Phylum Mollusca?????

Answer 1

Answer: General features: They are commonly called soft bodied animals. They are mostly marine, few fresh water and also found in damp soil. It is the second largest phylum in the animal kingdom. Body is unsegmented (except Neoplina) and bilaterally symmetrical (except few twisting forms like Pila). They have organ system grade of body organization. Body is triploblastic and haemocoelomte. Body is divided into three distinct parts; foot for locomotion, head bears sense organs and visceral mass (digestive and circulatory organs). Body is covered by calcareous shell that may be external (e.g. Pila), internal (e.g. slug, sea hare, sepia) and absent (e.g. sea lemon, octopus). Glandular fold of the body is called mantle or pallium. Mantle cavity or pallial cavity is located between shell and visceral mass.

Answer 2

Answer:

Phylum Mollusca

Molluscans are very diverse animals and form an important part of the ecosystem in the world. Some animals that you are familiar with like snails, octopuses, squids, oysters, clams etc. all belong to Phylum Mollusca. Did you know that Molluscs with shells can produce pearls? Some of these are also eaten by humans in different regions of the world. Let us educate ourselves about this phylum of the Animal Kingdom.

Characteristic Features of Phylum Mollusca

• They are bilaterally symmetrical.
• They are triploblastic, which three layers.
• They show organ system grade of organisation.
• The body is soft and unsegmented.
• Body is divisible into three regions – head, a visceral mass, and ventral foot.
• Body is covered by a mantle and shell.
• They can be found in different habitats, both aquatic and terrestrial.
• The body cavity is a haemocoel, through which blood circulates.
• The digestive system is well developed and complex. It has a radula, which is a rasping structure that has chitinous teeth. It is used in feeding.
• The nervous system is made up of paired ganglia, connectives, and nerves.
• The circulatory system is open, with heart and aorta.
• Respiration occurs through gills called ctenidia.
• The ventral muscular foot helps in locomotion.
• They have a pair of kidneys (metanephridia)
• Sexes are separate and reproduction is through sexual reproduction.
• Fertilisation can be internal or external.

Hope it helps!