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Photo copyright Tim Nicholson.
Nudibranch Coryphella browni taken on Chicken Rock, Isle of Man.
More nudibranch photos
The nudibranch, or sea slug, is one of my favourite
animals to spot underwater. They are often colourful
little creatures, advertising their toxicity to predators.
You find nudibranchs around the world, in temperate and
tropical seas, and even in the Antarctic. They are
hermaphrodites: possessing both male and female organs.
Some lay a single string of eggs, others produce coiled
flat ribbons. These are usually white but may be red,
pink, orange or other colours.
The nudibranch we're featuring today, Coryphella browni,
has a translucent white body and numerous pretty coloured
pointy projections (cerata), with white tips, on its back.
It feeds on hydroids, which are simple stinging-cell
animals related to corals and sea anemones. It not
only doesn't mind their stinging cells, it actually
puts them to use. The nudibranch passes the intact
cells through its digestive tract and out to the cerata
tips. Any animal taking a bite out of the cerata will
cause the stinging cells to discharge, then give up and
go and eat something less painful.
Coryphella browni is up to 5 cm long and occurs around
the British Isles and Northern Europe. Its egg masses
are laid in a wavy spiral near its hydroid food.
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