A male shark possesses a pair of claspers which are inserted into a female shark’scloaca (an opening on the underside of the body)at the time of mating. Claspersare located on the inner edge of the pelvic fins near the male’s cloaca. The function of claspers is to introduce sperminto a female shark’s body for the purpose of fertilizing her eggs. Female sharks do not have claspers.

Acoelomates are animals that have no body cavity or coelom. The examples are poriferans, coelenterates,ctenophore, platyhelminthes. Pseudo-coelomates are animals that has false or pseudo coelom. Examples are aschelminthes. Coelomates are animals that has true coelom enclosed by mesoderm on both sides. Examples:from annelida to arthropoda are coelomates. Henceroundworms are pseudocoelomates, molluscs and insects are coelomates while flatworms are acoelomates

Triploblastic condition can be seen in flat worms.Ctenophores, sponges and corals are diploblastic.

Spongilla is a fresh water sponge that belongs to phylum porifera. It has special collared cells called choanocytes.Choanocytes are not found in leech, dolphin and penguin

Fasciola, a flatworm has a single body cavity to the outside that serves both as mouth for ingestion and anus for egestion of undigested food. This is known as blindsac plan.

Lampreys and hag fishes are unusual, jawless fish that comprise the order Cyclostomata, so named because of the circular shape of the mouth. The brains of lampreys and hag fishes differ a lot, but they also show a large number of similarities, as do all craniate brains

Aschelminthes is bilaterally symmetrical and triploblastic. These are mostly aquatic,free living orparasitic.Their body is three layered which is ectoderm,mesoderm and endoderm