Andy Cornish's Blog

Dr Andy Cornish was raised in Hong Kong, and gained a strong interest in wildlife through spending time in Pokfulam Country Park. He studied Zoology at Nottingham University in England, travelled extensively through Central America where he learnt to scuba dive, and later did his PhD on reef fishes at the University of Hong Kong. Since then, he worked for a year doing coral reef management for the government of American Samoa, and taught in the Dept. of Ecology and Biodiversity at the University of Hong Kong. He worked at WWF from 2005 to late 2012 as Conservation Director, and was responsible for four programmes: Climate, Footprint, Local Biodiversity and Regional Wetlands (including management of the Mai Po Nature Reserve). He remains involved in environmental issues on an independent basis.

What mates at South Bay?

Sea Hares!
May 4, 2013

They may have a face only a mother could love but I was delighted to find dozens of Ragged sea hares just off the beach at South Bay earlier in the week while testing some new camera gear. Even better they were laying eggs on algae in just a few metres of water.

I have only ever seen sea hares in Hong Kong in the colder months and rarely dive in the winter these days, so havn’t seen any for years. I do know that there is a scientific paper on the species occurring in Hong Kong, and that several new species were described from specimens collected locally, but can’t put my hand to it. Fortunately this species (Bursatella leachii) is quite easy to identify from its numerous long, branching fleshy papillae and spots, which locally at least are blue. It occurs in all tropical seas of the world but there are believed to be around 8 sub-species, all a little different.

I’ve often wondered what happens to sea hares during the summer months as this animals were up to 15 cm or so, and quite conspicuous. I found out from this website that that is around the maximum size for this species and that sea hares may only live for a year so it seems they die off. Also that as you might expect for a marine animal that moves slowly and that has no physical defence, it secretes a poison but also interestingly, can also squirt ink like a squid or octopus. Lastly, those eggs that were being laid will hatch into tiny planktonic larvae in a week, and drift around the ocean for up to two and a half months before coming into shallow waters, attaching to the seabed with mucus and metamorphosising into miniature adults.

It just goes to show that there is a wealth of fascinating marine creatures even at our public beaches, if you’re curious enough to look!

Andy

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