The 12 Critters of Christmas

Stop light loose jaws bright red glow lets them see more that the average deep sea fish.

Find out more:

Stop Light Loose Jaw at the Natural History Museum.

James - My name is James Maclaine and I work as a curator at the Natural History Museum in London. And I've seen many, many weird and wonderful fish, but one of my favourites is a thing called the stop light loose jaw, which is a deep sea fish and it has some very unusual abilities.

It's found all round the world in all the main oceans, the Pacific and the Atlantic, and it like many of the fish living at depths like that is capable of producing light. It has two different lights on its head, one behinds its eye and one a bit further back behind its jaw. 

And one of these is blue, which is not unusual, a lot of the fish and other organisms at that depth use blue light because it travels quite far through the water, it travels further than any other kind of light.

But the really unusual thing about the stop light loose jaw is that it also has a read light and it's one of only three kinds of fish that can do this.

And the unusual thing about it is that hardly anything else can see it, everything's eyes are tuned to blue light. So the red light that's produced by the stop light loose jaw is pretty much invisible. So it has its own private wavelength of light. 

And we're still not totally sure what it uses it for. It could use it like a torch, to sort of, shine ahead of it as it's swimming around looking for prey. Or it could even use it to communicate with other stop light loose jaws and of course everything else would be oblivious.

The thing I really like about it is just its really fearsome appearance. I can remember as a small boy seeing pictures of deep sea fish the stop light loose jaw in books and just thinking these, maybe huge monsters living in the bottom of the sea and only recently I found out that they're, you know, pretty tiny compared to a lot of the other things that people know about lie sharks and things - they're fairly small.

But yeah, they look like nightmarish creatures. They have these big huge fangs and they're very weird looking. So, I think that's one of the things that appeals to me about it. And I quite like the mystery of it. Although we can make educated guesses about what it's doing with its light, we're not 100% sure and we may never be because it's very, very hard to go down to that depth and watch these things behaving naturally.

So it could be doing things with it's lights that we just would never have dreamt of.

We meet the dugongs and manatees, those mysterious marine mammals that were once mistaken for mermaids.

Find out more:

West Indian Manatee, at the Florida Museum of Natural History

Sarah - Well, we've reached our Christmas critter number four, and I've chosen some gentle giants. The dugongs, and their close cousins the manatees.

These are the sirenians, a group of marine mammals that evolved from four legged ancestors that took to the sea around 50 million years ago and supposedly were mistaken by sailors for mermaids... hmmm... not sure about that, maybe they'd been at sea for way too long.

well, they have a host of adaptations to an aquatic life - they have very dense bones that act as ballast, and huge lungs that take up two thirds of their body length, which they use to control their buoyancy.

And they've earned themselves a reputation as the dummies of the marine mammal world, because their brains are only the size of a cricket ball - which in actual fact is probably an unfair label, because they can be trained to perform similar tasks as their more famously intelligent cousins, the dolphins.

It might be not so much that dugongs and manatees have tiny brains but that they have evolved super-sized bodies that keep them warm and provide enough space for a huge stomach to digest all the tough seagrass and vegetation they eat. 

There are four living sirenian species - a single dugong species lives in the Indian and Pacific Oceans, there's the west African manatee, and the west Indian manatee that lives around the Caribbean, plus a third species that's evolved to tolerate freshwater in the Amazon river.

But there have been lots more sirenian species in the past - there are around 50 extinct fossil species known of, and one of the biggest was the Stellar's Sea cow. That one grew to a gigantic 8 metres in length and used to live across the North Pacific until people hunted them to extinction because they were just too tasty and being such slow, docile creatures they were too easy to catch.

Helen - And I guess not many people hunt manatees and dugongs today, but they do face various threats still, don't they? 

Sarah -  Yep, there are problems like getting hit by boats as well as habitat loss - they eat a lot of seagrass and other vegetation that's under threat globally. And then last winter, a lot of manatees in Florida died because the temperature plummeted - seems they are sensitive creatures.

And Helen, do you know how to tell the difference between a dugong and a manatee?

Helen - It's their tails isn't it?

Sarah - Yeah, that's right  - Manatees have a spoon shaped tail, while Dugongs have fluked tails more like a dolphin.

Mantis shrimp have a lightening fast punch and the most complex eyes in the animal kingdom.

Sarah - For our 6th Xmas critter we're going to be venturing out to the tropical coral reefs for one of my personal favourite species, which is the mantis shrimp.

These are like the Kung Fu masters of the ocean world. They're found all around the world in both tropical and subtropical seas.

They range from only just a few cms, so a couple of inches long, up to around 30cm, which is about 12 inches. And they can shoot out their front claws which are either shaped like spears or clubs, which is why they earned the names mantis shrimps because they look a little bit like preying mantises - and they can shoot those out at around 23m/s with an acceleration of over 100,000 m/s2, which is equivalent to the speed of a speeding bullet.

And they also have the most elaborate and complex eyes of any animal on the planet.

So let's start with their claws. Different species use their claws in different ways. Some have these barbed, spearing claws to jab out a soft prey like fish. And others have club-like claws that they use to break open harder prey like snails and crabs.

These claws shoot out from the mantis shrimp so fast that they actually create little collapsing bubbles that make a pop like a small sonic boom. And they can even sometimes produce a tiny bit of light as the energy produced is so high.

The shock wave created by the bubbles collapsing is actually enough o stun the prey so even if they don't hit it with their claws they can still get it afterwards.

Not that they would be likely to miss their prey with their claws because of their incredible sense of vision.

Like other arthropods including other crustaceans like crabs and lobsters as well as insects and spiders, mantis shrimps have compound eyes.

These are made up of lots of tiny little eyes called omatidia, each with its own lens and light and colour-sensing pigments. 

We have 4 different types of photoreceptor pigments in our eyes. One type in the rod cells that senses the brightness of light, and 3 types in the cones that detect different wavelengths of coloured light.

Mantis shrimps have 16 different types of pigments. They can see infra red, and ultra violet light as well as polarized light. And the position of their eyes on movable stalks also means they have accurate depth perception. Obviously very useful for aiming your strikes at your prey.

So, although they're quite small, those mantis shrimps, you certainly wouldn't want to mess with them.

Another name for them is thumb splitters because they can give a nasty injury if you get them annoyed.

Should turkey fish - also known as lion fish - be on the Christmas menu?

Find out more:

Invasive lionfish in the Florida Keys (NOAA)

Helen - Well, from one elegant creature that you need a microscope to appreciate to another stunner that can easily be seen with the naked eye.

My next critter has a slightly tenuous connection to the festive season, but it's sometimes called the Turkey fish - it's also known as the firefish, scorpion fish, but probably it's most well know as the lionfish.

These beautiful, graceful denizens of coral reefs are quite easy to spot, they tend to be covered in red and white stripes and they dress themselves in a costume of long white spines that stick out in all directions, which you should steer clear of because each spine is tipped with a dose of nasty poison -although they tend not to be deadly for people, but they are extremely painful, and lionfish use them as a means of defence.

Well, originally lionfish lived only in the Indian and Pacific Oceans, but around a decade ago, divers started spotting them a long way from home, in the Caribbean where it's thought they were accidentally - or maybe even deliberately released from aquariums - and they're now spreading throughout the region, stirring up controversy and altering the balance of ecosystems.

Because the problem is, that lionfish may be pretty to look at, but they are also voracious predators. One study revealed that after five weeks, lionfish can munch their way through 80% of the native young fish on a Caribbean reef. And a big worry is that in the Caribbean, lionfish have escaped the natural checks and balances, those predators, parasites, and diseases that in the Indo-Pacific prevent them from taking over. So we really could be facing a lionfish plague.

Sarah -  So, what's being done to try and deal with this invasion of lionfish?

Helen -  Well, a lot of divers are going out and collecting lionfish by hand - well, with spears and nets - and there are early response networks being set up, so that anyone who spots a lionfish can report it and a swot team of lionfish disposers can be on the scene to quickly whisk it away.

And people have started to work out they are also quite good to eat too... so maybe turkey fish should be on the Christmas menu.

Giant tube worms cope with many extremes in their homes on deep ocean black smokers.

Sarah - One of my all-time favourite species in the whole ocean is a kind of deep sea tube worm called Riftia.

They live at the deep sea vents in the middle of the Pacific ocean which can be up to several miles below the sea surface. They look a bit like giant lip sticks. They can grow up to 3m long, and they have this hard white outer tube and this beautiful bright red plume sticking out.

And they're actually an evolutionarily ancient lineage because there are examples in the fossil record dating back to at least the Cambrian which is over 500 million years ago.

The thing that I think makes Riftia special is that its got so many amazing adaptations to living in what we would think of as a really inhospitable environment down there at these hydrothermal vents. There's such high concentrations of toxic nitrates, hydrogen sulphides and really high heat levels.

First of all, let's think about how they get their energy. Down at this depth there's no sunlight so there's no photosynthesis which is how most food chains elsewhere in the oceans begins, which photosynthesizing species like algae and phytoplankton using sunlight to make sugars. So how do Riftia survive?

They have a symbiotic relationship with a type of bacteria that can convert the chemicals spewing out of these black smokers like HS into organic molecules that provide energy for the worms by a process called chemosynthesis.

The worms them absorb these nutrients directly into their tissues so technically they don't actually eat anything which is actually quite an unsual thing for an animal, not to eat, it's able to absorb its nutrients, especially for something that size.

The worms also have a high tolerance for concentrations of sulphides and nitrates that would be deadly to most other animals. The deep rich red colour of their plumes comes from haemoglobin which is the same sort of molecule that makes our blood red but their haemoglobin is differently structured and it's able to withstand high levels of sulphide still allowing it to carry oxygen around the worms body.

They're also the fastest growing marine invertebrate. They can grow nearly 2m in less than 2 years.

But because they live at such depth there's not that much known about them and it means that there's always more being discovered about them.