In this article we will discuss about the structure of Balanus with the help of a diagram.
Fig. 237 BALANUS
1. It is commonly known as “rock barnacle” or “acorn barnacle” and is sessile and blind and found in sea attached to rocks or stones.
2. Body is surrounded by a hard calcareous shell comprising of two pairs of carino-lateral plates on lateral sides, an unpaired median rostrum above and an unpaired median carina below.
3. The opening of shell is closed by scutum & tergum.
4. The cephalic appendages include mandibles and maxillae.
5. The thorax has no segmentation but bears six pairs of birmous appendages.
6. Abdomen almost absent but a minute caudal ramus is present near the penis representing the abdomen.
7. An unpaired compact ovary is situated at the base of stalk and the highly branched testis lies in the throacic region.
8. Sexes are united. Egg develops in the mantle cavity of parent and results in the release of a free swimming nauplius larva.