Sea Squirts:  Sperm Warfare

Life under the waves can get pretty crowded when you are a sea squirt vying for space on the rocks. But these sea creatures have a novel weapon--they use their sperm to sabotage the eggs of other kinds of sea squirt. According to a marine biologist in California, this may be the first example of sperm competition between species.(Extract from the New Scientist)

Some classification notes

Tunicate Mailbase EForum
 
 

Sea Squirts are fouling organisms on wharves and piers Ciona intestinalis

Lightbulb Sea Squirt, Clavelina lepadiformis

News Reports
 
 
 

27 September 2009
On a dive out of John o' Groats (the most northerly settlement of mainland Scotland) I discovered the rarely reported free swimming tunicate Thetys vagina as well as the Mauve Stinger Jellyfish, Pelagia noctiluca,  both seen in shallow (10 metres deep) water, within two or three metres of the surface. Thetys was observed swimming by opening and closing its mouth and propelling itself along under the cliffs at Skirza Head (eastern coast).

Thetys vagina has been rarely recorded in Irish waters. The species was reported for the first time in Irish waters during November 1988 when hundreds of specimens were taken in trawls at offshore. A few specimens were also found stranded on Ventry Beach, near Dingle, County Kerry during July 1987 & 1988.

Corella eumyota

Whilst accompanying the biologists in St. Peter Port Harbour, I found many Goniodoris castanea sea slugs with their spawn. They were feeding on the colonial Star Ascidian, Botryllus schlosseri,  and were cryptic.  On one 5 x 5 cm
square colony of Botryllus schlosseri I found six of these nudibranchs. Dr. Charles David, President of La Société Guernesiaise, tells me this species is a new record for Guernsey.