How do mollusks reproduce?
Mollusks are primarily of separate sexes, and the reproductive organs (gonads) are simple. Most reproduction, however, is by sexual means. Eggs and sperm are released into the water by members of some (primitive) species, and fertilization occurs there.
What type of digestive system do mollusks have?
6. Clams (and all mollusks) have a complete digestive system. It consists of a mouth where food is ingested, a short connecting tube called the esophogus, a stomach which temporarily holds food, and an intestine where food digestion and absorption takes place.
Are Cnidaria bilaterally symmetrical?
Comparative analysis provides evidence that bilateral symmetry is a primary character of Cnidaria. All anthozoan taxa are characterized by bilateral symmetry. The bilateral symmetry of Cnidaria is thought to be inherited from the common ancestors of both cnidarians and triploblastic bilaterians.
Is Mollusca asymmetrical?
Animals in class Gastropoda (“stomach foot”) include well-known mollusks like snails, slugs, conchs, sea hares, and sea butterflies. These animals are asymmetrical and usually present a coiled shell.
How many eggs do mollusks lay?
The number of eggs laid by an individual varied from 2 to 25, but may have been as high as 40.
How do you mollusks grow and develop?
Depending upon environmental conditions, the eggs hatch within about two weeks. Larvae, called rhynchoteuthion, emerge. During development, the larvae forms two tentacles and the eight arms grow in length. As an adult, the male squid will fertilize the females eggs and the spawning process will begin again.
What defines Mollusca?
Medical Definition of Mollusca : a large phylum of invertebrate animals (as snails, clams, and mussels) that have a soft unsegmented body lacking segmented appendages and commonly protected by a calcareous shell.
What type of circulatory system is found in most mollusks?
open circulatory system
Most mollusks have an open circulatory system but cephalopods (squids, octopus) have a closed circulatory system.
Which of the following does a mollusk use for movement?
Most mollusks move with a muscular structure called a foot. The feet of different kinds of mollusks are adapted for different uses, like crawling, digging, or catching prey. Many mollusks have an organ called a radula (RAD you lah), which is a flexible ribbon of tiny teeth.