Home Renovations

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Apparently one stomatopod wasn’t too impressed with his new home in the lab. So he took matters into his own “clubs”. He punched away at the plastic at one end of the cavity to make a second entrance.  The photo shows the damage he made to the lid (the lid is screwed onto one end of a tube, the other end has an opening for the stomatopod to enter and exit).

If the field, I think they punch away at the rubble that they live in too. By doing this they can make the cavity into the shape they like and they can expand it if it isn’t big enough for them. However, it’s unlikely that they create the hole from scratch, other animals (e.g. boring sponges) probably start the cavity. Stomatopods just renovate.

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Today Is A Special Day

Today is one of the record books. Write down the date, petition your government for an international holiday, shout from rooftops, tweet all your friends, throw a parade! Why? Because today I caught my 100th mantis shrimp!

Shrimp 100a

Meet mantis shrimp 100. She is a medium sized shrimp at about 30mm long and is obviously quite cute. I found her in a little piece of rubble in a seagrass bed, just off the back of the island. She doesn’t seem overly aggressive because she didn’t try to punch me as I extracted her from the rubble (which makes me like her even more). She also is quite the model, as she sat still whilst I was photographing her. Pity I don’t have a macro lens to get even better photos.

Shrimp 100

Mantis shrimp number 100 is a very special lady stomatopod, so I think we should name her. Any suggestions?

Shrimp 100b

Bioluminescence and Ostracods

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Photo: An ostracod releasing a bioluminescent mixture. Elliot Lowndes

I just saw some tiny flashing lights in the water at Carrie Bow. This phenomenon is known as bioluminescence which is when an organism produces and emits light (e.g. fireflies).There are many bioluminescent marine organims including fish, squid (even my past study species, the dumpling squid), crustaceans, jellyfish and tiny single celled algae. The light is produced via the chemical reaction of luciferin (a pigment) with oxygen. An enzyme (luciferase) is required to speed up the reaction.

Most marine species produce blue or green light via this reaction. This is because these are the wavelengths that travel the greatest distance through seawater. If you’ve ever had a chance to dive, you’ll notice that red is the colour that disappears first. However, there are some species that produce red, yellow or even infrared light such as some fish, worms and jellyfish.

But what are they using this light for? Some species (including dumpling squid), use it for counter illumination. This means, that when they are swimming around at night, they emit a some light downwards as camouflage. This diminishes their shadow so that any predator looking up won’t see (and try to eat) a squid shadow above them. If you’ve seen Finding Nemo you will be aware of another use: prey capture. Anglerfish lure prey towards their mouth with a glowing bulb.

The final use I want to mention (although there are other uses such as distraction or use as a warning signal), is courtship. Now, I am not sure what was in the water tonight, but it could have been ostracods, a small marine crustacean which is found around here. Male ostracods squirt out a bioluminescent mixture into the water. They do this about an hour after sunset over shallow seagrass beds (which is where I saw it tonight). They’re doing this to attract females.

Usually males produce several pulses of light, the pattern of which varies among species. The cool part is when he swims upwards in a spiral, releasing light pulses a regular intervals. The female uses the position and the timings of the light pulses as a way to determine the males position, intercept him and mate with him. Of course, she only does this if she likes his light pulses. It amazes me that such a tiny organism can use these light pulses to calculate the future position of a male, the distance she is from him, and then the direction she should swim in to intercept him. Pretty awesome!

Even though I’m not sure that it was ostracods in the water tonight, I would like to think that it was and that I was watching some little male love songs in the seagrass below.

Turtle Visit

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It might not look like much in the picture, but the sand thrown on the bench chair, the step and roughed up on the ground is due to a turtle! We’re not sure yet if it’s laid any eggs here. If it has laid eggs, we will mark the spot so that no-one walks over it. So far this trip, we’ve have a turtle visit almost every night; Thursday night there were five turtle digs on the north end of the island! Although none had eggs.

Stomatopod Punching Bag

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Photo: Stomatopod aggressive display. Although usually they pull their arms further out to the side. The arms are the parts that have the small purple spot on them. Hopefully I’ll get a better photo soon!

Stomatopods are aggressive creatures. They have deadly weapons which can punch as fast as a .22 bullet and they do not hesitate to use them. In fact, I’m quite glad I work with a small species, otherwise I would have needed several stitches by now.

They do not only direct their aggression at me, but frequently it is directed towards another stomatopod. However, they don’t tend to go straight to the punching, they do some fierce displays first. Like many other animals (think frilled neck lizard), they try to make themselves bigger to appear more fearsome. They pull their raptorial appendages (these are the punching arms) out to the side and lift their body up. This could happen a couple of times before anything more brutal.

If neither runs away after this display, then things get more physical. One will move towards the other one, and, if it doesn’t lose its nerve, will try to punch its opponent! In many cases one will punch, then quickly curl up into a defensive ball, in case the other one retaliates. Sometimes they will exchange several punches before one admits defeat and runs away.  Probably a good move since they are known to sometimes kill one another in these fights.

These interactions are over very quickly and there’s always a clear winner. In Belize I spend most of my days watching stomatopods behaving aggressively which hasn’t (yet) got boring. Such feisty, charismatic critters.

Lysiosquillina lisa

This is a fantastic post by ScubaNomad about a large burrowing mantis shrimp. Includes a great photo and good info. What more could you want?!

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Lysiosquillina maculata.  This is a rarer species of Mantis shrimp found only in a small region in the South Pacific from the Andaman Sea to Papua New Guinea.  I found this on a muck dive in the Yasawas in Fiji an area not currently in their reported range but just to the south of it.   It was quite photogenic besides the fact it tried to spear my camera.  I found this down around 18M.  The best distinguishing features for this species are: Bilobed eyes with white spots, raptorial appendage dactyl with 9–10 teeth, unusual reddish brown color.  The colors were quite striking with large transverse reddish brown and cream stripes and antennal scales cream with reddish brown patches in center.   While they are commonly referred to as shrimps they are not actually Decapods but are a separate order, Stomatopoda.  They live in large u-shaped burrows (up to 10…

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