Species of the month – lions of the sea

Any guess what this is?


It is, of course, a star-forming region in the carina nebula, courtesy of NASA, ESA, N. Smith (University of California, Berkeley), and The Hubble Heritage Team (STScI/AURA).

How about this?


(C) Lisa Kamphausen/SNH

Imagine a sunny warm day on the beach. You take off your clothes, feel the sand between your toes, run off into the gently rolling waves and… squirm! Swimming in jellyfish-soup is never a pleasant experience. And it can be painful too, if you are unlucky enough to get caught-up in the tentacles of a lion’s mane.


Lion’s mane in Scapa Flow, Orkney, (C) Lisa Kamphausen/SNH

So it is no wonder that jellyfish are some of the more under-appreciated animals in our seas. But a closer look, if you dare take it, does reveal some surprisingly beautiful details. Our marine team bump into them a lot on surveys.

Far from featureless blobs, lion’s manes are extraordinarily well adapted to life in the sea. They live in the freezing cold waters of the Arctic and Northern Atlantic and Pacific Oceans, and are rarely found further south than 42 degrees latitude (that’s around northern Spain or Rome).


Close-up of lion’s mane, (C) Lisa Kamphausen/SNH

Jellyfish have been around for over 650 million years – they were there floating around before even the dinosaurs. So whatever it is they are doing clearly works very well.

Their internal structure may seem simple, but it does what it needs to. Instead of an energy-hungry brain, jellyfish have a loose network of nerves and receptors which can detect stimuli such as touch and light – so they know which way is up and down using the light of the sun, or whether they have caught prey which they engulf with their tentacles and pass into their mouth. They do have a simple digestive system, but don’t need lungs: gases can just diffuse through their thin skin.


Lion’s mane off Arran, (C) Lisa Kamphausen

Arctic lions manes are some of the biggest animals on the planet: their bells can grow over 2 meters in diameter, with tentacles of 30 meters. Luckily for us, the further south you go the smaller they get. In Scottish waters the ‘normal’ lion’s mane (Cyanea capillata) is usually 30-50 cm across, while the blue lion’s mane (Cyanea lamarcki) is even smaller.

And since jellyfish make good use of ecological niches freed up by collapsed and fished-out fish stocks, it might be worthwhile starting to appreciate them. Turtles find them tasty -leatherbacks live almost exclusively off them. Tempted? Nah, didn’t think so. They do look amazing though.

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