Photo credit: Jackie Hildering

 We've had many of these remarkable creatures around in the last weeks.  They can be seen swimming right by the dock in Telegraph Cove.  They are hooded nudibranchs (Melibe leonia)  and are up to 10 cm long.  A nudibranch is a type of sea slug that has naked ("nudi") gills ("branch").

Our area has some 200 different species of sea slug and the hooded nudibranch is one of the most unusual looking species, not looking like a slug at all.  Many mistake the hooded nudibranch for a jellyfish but it does not have stinging cells like jellies do.  The animal's large disc-like head lets it feed on plankton and small crustaceans and the lobed structures on the animal's back are the naked gills.  If a predator goes after a hooded nudibrach, it can swim slowly by undulating its body back and forth.  If the predator goes after the gills, these detach and stick to the predator's mouth, causing distraction.

There are so many hooded nudibranchs around Telegraph Cove at this time of year as they collect to lay eggs.  It is an amazing sight to see groups of 100s of them collecting on the kelp.  Since sea slugs can only sense light and dark, the way they find one another is by releasing pheromones.  They send out a watermelon-like scent that then attracts other hooded nudibranchs.  After mating, both animals lay eggs since they are hermaphrodites and then they die. 

The image on the right shows some of the egg masses.  Each cluster of eggs is only about one centimeter wide and contains thousands of eggs that will hatch to be plankton.  From whales to sea slugs - this area is amazing in its biodiversity!

For more information on the hooded nudibranchs - see http://www.seaslugforum.net/message/20127