I’m surprised that I haven’t gotten around to posting this yet. Here is one of my favorite mantis shrimp videos of all time.
This segment was a bit of humor produced for ‘The Fastest Claw in the West,’ a documentary from 1985 about mantis shrimp. It is narrated by blog-hero David Attenborough, and features stomatopod expert Roy Caldwell. It turns out you can watch the whole thing on Youtube. It’s great fun and very informative. I highly recommend it:
All arthropods need to molt. Here is a time lapse video of how a spider crab does it.
When a crab is ready to molt it rapidly takes up water, causing pressure to build in its body cavities. The rigid outer exoskeleton breaks open and the crab is able to push itself out from inside its molt. The new exoskeleton is softer, so it is undamaged by the increase in body volume, but it will eventually harden over time. Recently molted, soft-shell blue crabs are commonly steamed and eaten whole in my neck of the woods.
In contrast to the pretty and placid G. playtsoma, today I have a photo and video of one of the meanest mantis shrimps I have encountered. Gonodactylus chiragra occurs in the same intertidal reef flats as G. playtsoma, but its temperament is the polar opposite. It hits hard and often.
You lookin' at me?
Its coloration is a mottled brownish-yellow-green on creme; except for bright orange and yellow accents on the antennae, mouthparts, and walking legs.
Here is a quick video of G. chiragra, whalloping the wall of its aquarium; attempting to hammer my finger (off-screen). It plays at regular speed and then at one-tenth speed (the slow-mo is much more impressive and/or comical, in my opinion).
I first saw this species of stomatopod in the field this year. They are really beautiful animals, with subtle but vibrant color accents on their dactyls, antennae, eyes, and on the edges of some of their somites (body segments). This individual is about 72 mm in length, and the species seems to be fairly docile (for stomatopods).
This animal also has very beautiful fluorescent patterns on its body:
G. platysoma; UV-excited fluorescence.
I talked previously about fluorescence in stomatopods here. However, I don’t know if the patterns on G. platysoma are used to amplify any particular signals. These animals live in shallow water and would have less use for fluorescent signal amplification.
Disney Nature has a new IMAX documentary out titled, ‘Oceans‘. A quick survey of the reviews of the film indicates that a mantis shrimp, Odontodactylus scyllarus, is a part of the most memorable sequence of the film. Here is a clip of the mantis shrimp’s scene, (available in 1080p on Youtube). Near the beginning there is a really nice shot of the pseudopupil (the facets of the eye looking directly at the observer).
I, however, have a couple criticisms of this sequence. First off, this was almost definitely shot in an aquarium. Secondly, what is it with IMAX movie makers and repeatedly pushing animals towards stomatopod burrows until they lash out? Similarly to the sequence from ‘Deep Sea 3D’ where an octopus is forced to approach the burrow of a Hemisquilla californiensis, the mantis shrimp in this video shows no interest in predating the crab. He just seems to be trying to get the crab away from his hole. Normally, the crab would surely oblige if it wasn’t for the Disney filmmakers repeatedly pushing it back.
I can’t help but be reminded of Disney’s ‘White Wilderness‘ documentary where the filmmakers pushed lemmings off a cliff into the ocean in order to convince people, incorrectly, that lemmings engaged in suicidal behavior. They are quite a viscous bunch over in the Magic Kingdom.
Spiny lobsters, Panulirus argus, have an unusual and poorly understood migratory behavior. Every autumn, many of the shallow living lobsters around the Bahamas begin forming traveling queues that aggregate into long chains of marching lobsters. These chains can swell to thousands of individuals as the animals migrate to deeper waters.
Our main man, David Attenborough, breaks it down and somehow manages to make a skittering train of lobsters feel epic:
As mentioned in the video, the migration possibly occurs in order for the lobsters to escape turbulence and turbidity in the shallows resulting from autumn storms that sweep into the Bahamas. The migration has long been observed in tight correlation with these storms. Following the first storm of the year, the spiny lobsters begin amassing at buildup areas and prior to embarking on the mass migration. The cue to begin queueing (hah) is likely the sharp water temperature drop following the first storm. Indeed, in laboratory observations, decreases in water temperature increased queueing among captive spiny lobsters.
The purpose of the lobster queue formation during migration is likely twofold. For one, traveling in a line reduces water drag for the lobsters traveling behind others. To borrow a term from racing, the lobsters are drafting on the wakes of their line-mates. In this manner, the lobsters conserver energy and momentum on their trek. The other reason for forming the migration queues is likely predator defense. Beyond projecting increased size via aggregation, the lobster queues can rearrange into a defensive circle to cover their vulnerable back-sides. You can see an example of the onset of defensive formations in the photo below.
Panulirus argus migratory train. The lobsters at the front of this train were perturbed by the divers, causing them loop back into the train, creating a lobster vortex. Adapted from Kanciruk and Herrnking, 1978.
References:
Kanciruk, P and Herrnkind, W. 1978. Mass migration of spiny lobster, Panulirus argus (Crustacea: Palinuridae): Behavior and environmental correlates. Bulletin of Marine Science, 28(4): 601-623,
I am going to start a running catalogue of the diverse arthropod microfauna of my reef tank. Here is my first attempt to capture one of these tiny animals. This is a sediment-dwelling ostracod, about 250 microns in carapace length.
Ostracod, the white stuff around him is detritus.
I know, ugly photo, but this was a first attempt. Can anyone ID it further? The rubble in the tank was aquacultured on the gulf coast of Florida, but this little guy could have hopped on at the fish store.
I haven’t had much time to write this week on account of wanting to graduate someday. Here is one of the animals that I’m working on at the moment.
Neogonodactylus bredini
N. bredini is the easiest mantis shrimp to find on the east coast since they commonly hitch-hike on reef rubble, cultured in Florida for the aquarium trade. The photo above shows the ‘smasher’ raptorial appendage nicely, as well as the black pseudo-pupil (the facets of the eye that are directly facing the camera). These guys come in a bunch of different color morphs including the rusty color above, green, and grey mottled.
I’m trying to improve my photography skills, but the old Olympus C-5050 I’m using isn’t cutting it any more. It’s no fun trying to manually focus on a moving critter using a 1.8″ 110,000-pixel screen.
_________________________ Edit: Correction, this animal is actually N. wennerae. This species is physically indistinguishable from N. bredini. The only reliable determinant other than genetics is habitat depth.
Mantis shrimp use a variety of visual signals in order to communicate with one another. One set of commonly used signaling structures are the antennal scales; flattened, paddle-like structures derived from the second antennae and set on either side of the mantis shrimp’s head. They have a wide range of motion and can be directed at other mantis shrimp as part of intraspecific threat and mating displays. The antennal scales are often adorned with attention grabbing color and polarization patterns that stand out to other visually adept mantis shrimp.
Attenuation of light in water. Adapted from Levine and MacNichol, 1982
However, the deep ocean is not kind to color contrast. As you move deeper, the absorptive and refractive properties of water attenuate the spectrum of available light. Longer and shorter wavelengths are filtered out until eventually the only available light is blue-green, around 480 nanometers in wavelength (left). Despite this limitation, some deep water mantis shrimp have found a way to preserve their color signals in an essentially monochromatic environment.
Lysiosquillina glabriuscula has bright yellow spots on its antennal scales and the underside of its carapace. This species is found in the shallows as well as at greater depths. It turns out that the yellow spots contain fluorescent materials that are stimulated by blue light and emit yellow light, similar to the yellow reflected light that the spots produce in white lighting. Therefore, these mantis shrimp are able to preserve their yellow spot signals at depths where there is only blue light available.
L. glabriuscula in white light (left) and blue light (right). Blue light is filtered out in the second picture in order to better show the green and yellow fluorescence on the animal. Adapted from Mazel et al., 2004
References:
Mazel CH, Cronin TW, Caldwell RL, & Marshall NJ (2004). Fluorescent enhancement of signaling in a mantis shrimp. Science (New York, N.Y.), 303 (5654) PMID: 14615546
Arthropoda 