CLASSIFICATION OF SACCULINA
PHYLUM :- ARTHROPODA (Jointed appendages.)
CLASS :- CRUSTACEA (Thick exoskeleton, antennae 2 pairs)
SUB-CLASS :- CIRRIPEDIA (Sessile adults without compound eyes and antennae, with carapace and mandibular palps and with 6 pairs of biramous thoracic limbs)
ORDER :- RHIZOCEPHALA (Parasitic Cirripedia on decapod Crustacea.)
GENUS :- Sacculina (The root-headed barnacle)
It has cosmopolitan distribution.
HABIT AND HABITAT
Sacculina is a very interesting animal as it shows extreme case of degeneration or specialization due to parasitism and also it causes castration in its host.
GENERAL CHARACTERSTICS OF SACCULINA
- Commonly called as root-headed barnacle.
- Parasitizes crabs. Zoologists were able to discover its real crustacean nature by studying its embryology having first stage nauplius larva.
- Adult loses all arthropodan characters and appears like a fleshy tumour attached to the abdomen of the crab on ventral side and lead a parasitic life on decapod crustaceans.
- Sacculina through peduncle sends root like processes like mycelium of fungus in each appendages of the crab and in the body to derive nutrition.
- Appendages, segmentation, mouth, anus, alimentation absent.
- Presence of Sacculina causes development of many changes in secondary sexual characters of the host.
The nauplius larva resembles that of other crustaceans but without alimentation. Nauplius is free swimming and changes to next larval stage called Cypris larva. It attaches itself on decapod crab and then discards its shell and burrows into the host’s body. It becomes a mere mass of cells that passes in the crab’s blood stream, attaches to host’s intestine and grows. When the crab molts, part of parasite protrudes in the abdomen’ as an ovary packed with egg. The remaining part of Sacculina becomes branched ramifying throughout the host’s body and absorbing nourishment. The host neither grows nor breeds because its sex organs degenerate due to crab. This is called as parasitic castration.
The animal contains round mass of cells and all above characters hence it is Sacculina.