Barnacles

Permanently Attached and Parasitic Cirripedes

© John Blatchford

Barnacles (and two Terns), John Edwards

Some barnacles burrow into the shells of molluscs and dead coral, others are fully parasitic - but most live on the sea shore.

Burrowing Barnacles

There are about forty species of barnacle that burrow into a variety of substrates. They have separate sexes, but the males are small ‘parasites’ found only attached to females. This phenomenon fascinated Charles Darwin (who wrote the definitive monographs on living barnacles in 1851and 1854), and it made him start thinking about how such a way of life could come to be.

Parasitic Barnacles

Some barnacle species have become fully parasitic, usually on other crustaceans. The adults have no real body-form and only exist as root-like threads that fan out through the host’s body to feed. It is only when they reproduce that their larvae show that they are barnacles (typical barnacle nauplius or cypris larvae).

Commensal Barnacles

There is a way of life between ‘parasitic’ and ‘free-living’. Some barnacles live only attached to other animals but do them no harm – they simply ‘hitch a ride’. These commensal species are found on a variety of marine animals, but the most famous are the twenty or so species that can be found on the marine mammals. One species (the Whale Barnacle (Coronula diadema)) is found only on the Humpback Whale, and it seems likely that it uses chemical clues to find them.

Free-living Barnacles

Most of the thousand or more species of barnacle live permanently attached to rocks on the sea shore where they filter plankton from the water. There are two types:

(See also my blog on ‘The Barnacle Heart’)

Other articles by John Blatchford


The copyright of the article Barnacles in Marine Life is owned by John Blatchford. Permission to republish Barnacles must be granted by the author in writing.


Barnacles (and two Terns), John Edwards
       


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