Severe cases can even lead to death. Best way to protect yourself from getting the flu? Get an annual flu shot. When is flu season? The flu season occurs in the fall and winter, but the virus can stay active year-round. Is the flu virus contagious? Yes, it is very contagious. You can have the flu for 1 to 4 days before you start feeling sick.
Some mollusks have bilateral symmetry. Mollusks include gastropods such as snails, bivalves such as oysters, and cephalopods such as squid. Some bivalves have bilateral symmetry. Some mollusks have bilateral symmetry. Mollusks include gastropods such as snails, bivalves such as oysters, and cephalopods such as squid.
For most mollusk, their shell is external including snails, scallops, oysters, clams and mussels. For other mollusk, like squid, and cuttlefish, they have a internal skeleton similarly to a shell. There are also some that do not have a shell at all, like octopus and slugs, with only a mantle for protection of organs.ollusks have a body without a cavity, has more than two layers of cell layers, tissues and organs. Mollusks are soft bodied animals with three main regions: head, visceral mass, and foot. The head of the mollusk contains the sense organs such as the brain. It has a pair of eyes, a mouth, sensory and nervous structures.