The List: Five extraordinary deep sea species

Until the 19th century, all we knew of the deep sea and its fauna was from examining odd specimens found dead at its surface. A number of expeditions later, as the National History Museum celebrates the richness of the ocean in a new exhibition, its curator James Maclaine reveals his five favourite unusual species of deep sea fish.

1. Stoplight loosejaw

As its name suggests, this fish has a very loose jaw, with sharp teeth. Its head can hinge backwards and its lower jaw shoots out to grab things. “Stoplight” refers to the two different light colours on its head: a green-blue light and a red one. Most deep sea creatures emit blue light to help them see. Only three types of fish can produce red light, which they use to search for little prey close to them.

2. Pelican eel

With its tiny eyes and enormous triangular mouth, this is a bizarre-looking fish. It lives up to 2,800m below the surface, where food is scarce, so if you find something, you’ve got to make sure you can catch it. Using its blue light to attract little animals, the pelican eel sits in the dark, wriggles its tail and just opens its bag-like mouth.

3. Black seadevil

This fish looks like a satanic potato. As is often the case with deep sea anglerfish, the female is far larger than the male. While she has enormous teeth and a blue light organ on a stalk between her eyes, the male is only about 3cm long, and all he really has are big nostrils. She carries him around, provides him with food, and can even control his bodily processes. When she’s laying eggs, she can send a signal for him to fertilise them.

4. Football fish

This anglerfish looks like a deflated football. The female is again bigger than the male: if she is the size of a football, he is about the size of a person’s thumb. Both have sharp, spiny scales all over their body, and a mouth full of fangs. One specimen in the exhibition came from the stomach of a sperm whale. I imagine that they taste disgusting.

5. Sloane’s viperfish

The viperfish is quite thin and has fangs so big that they don’t even fit in its mouth, Weirdly enough, it uses its light to hide itself because where it lives, around 1,000m below the surface, there is still a faint amount of light coming from above. As a smallish fish, what you don’t want is to be visible against that light. A lot of fish, therefore, have blue light on their underside and can adjust the intensity of the light, so that when predators look up they just seem to disappear. It’s like an arms race: everything is looking up and everything is trying to hide at the same time.

‘The Deep’, Natural History Museum, London, May 28-September 5,

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