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Shrimp Taxon

My taxon study was on “shrimp” (swimming decapod crustaceans) that are included in the order Decapoda (specifically, suborder Pleocyemata).
I also did a phylogenetic exercise on cake.
I would advise future students of B.O.B. to NOT pick shrimp as their taxon study.
You would probably end up eating more species during the trip that you would actually find in the wild.

My NEXUS FILE done on Mesquite! (It includes the Mesquite phylogenetic tree.)
Also, HERE I explain how I chose characteristics, why I think shrimp would be interesting to study, and some resources.
Finally, this is what I did with the shrimp after I was done taking notes on them.

Decopoda
The order Decapoda includes crustaceans with ten legs, which includes lobsters, shrimp, prawns, as well as many other infraorders. In some decapods one pair of legs is enlarged, forming pincers. Classification in Decopoda depends on gill structure and legs, as well as larval development; Decopoda is split into two suborders, Dendrobranchiata (prawns) and Pleocyemata (true shrimp, lobsters, crabs, and others).

Pleocyemata
This suborder includes all decapods which incubate fertilized eggs; these stick to the swimming legs of the female. It includes:

Stenopodidea – The coral banded “shrimp” go here (they are neither shrimp nor prawn)
Caridea – The infraorder Caridea is comprised of all true shrimp, and contains around 2000 known species. It excludes prawns (peneaids), which are distinguished by gill structure and different ways the second somite (main body division) overlaps the first or third somite. Under Caridea are the following superfamilies:

Alpheoidea – The pistol shrimp, some of which are associated with Gobies in mutualistic relationships, belong in this superfamily
Atyoidea
Bresilioidea
Campylonotoidea
Crangonoidea
Galatheacaridoidea
Nematocarcinoidea
Oplophoroidea
Palaemonoidea – Macrobrachium are included in under the family Palaemonidae, which is under this superfamily
Pandaloidea
Pasiphaeoidea
Procaridoidea
Processoidea
Psalidopodoidea
Stylodactyloidea

Freshwater species


MacroTaxon 1: Found at Lambir Hills National Park, caught in a simple bottle trap in a rocky, deeper part of the Latak Stream (part of Sg. Liam) in a “glide” area near a small waterfall. Assumed to have been scavenging at night. The species is notable for the very prominent bumps/spikes on its long, enlarged fore-claws. It also has three spaced-out rostrum spines at the base, and the rostrum itself forms a crease with the carapace above the eye. In general these seem more aggressive though that might just be due to the fact that I was only able to conclusively identify dominant males.

MacroTaxon 2: Found at Lambir Hills National Park, caught in simple bottle traps in rocky, shallow “riffle” and “glide” parts of the Latak Stream (part of Sg. Liam). Assumed to have been scavenging at night. Note that MacroTaxon 2 has a smaller claw:body ratio compared to MacroTaxon 1, as less claw spikes (but still bumpy), claws that end in more pointy, curved tips, and only two spaced-out rostrum spines at the base instead of three. It seemed like the most common adult species at Lambir, if it is true that shrimp coloration varies due to their diet and not genetics. Examples of two different-colored MacroTaxon 2 shrimp are pictured. Both have the same features as described for MacroTaxon 2. A living specimen of this species (of a redder tinge) was also found in a very small, isolated “stagnant” pool near the bottom of a short waterfall along Latak Stream, which it shared with a clawless female (assumed). When disturbed it would raise its claws as the female hid behind or underneath it. Typical behavior of MacroTaxon 2? I don’t know. But it was kinda cute.

MacroTaxon 3: Found at Lambir Hills National Park, caught in a simple bottle trap in a rocky, shallow part of the Latak Stream (part of Sg. Liam). Assumed to have been scavenging in the afternoon. Although it is probably still not fully developed because of its transparent body and thin exoskeleton, this was definitely a different species because of its different claw shape, lack of claw bumps/spines, and different number of static tail spines. The rostrum on this one is not very pronounced and there were no spaced-out rostrum spines (though there were teeth/ridges). Suspected juveniles of this species (shown) were found in many of the “stagnant” branching streams throughout the forest at Lambir, though I could only assume they were of the same species by the general claw shape (for all I know they could be yet another species). Really not much is known about its behavior.

Marine species

Coral Banded Shrimp (Stenopus hispidus): Picture courtesy of Greg. It was found about 5 meters underwater off of Gaya Island by Min-Sheng, by the dropoff. It was very shy and seemed to stay in this one crevice created by shelf coral and rock throughout our stay at Gaya Island. These shrimp also supposedly clean fishes and other animals, but since I was unable to stay so deep underwater (it resided at about 5-7m deep) for a good amount of time I couldn’t observe this behavior myself. Note how the most prominent claws aren’t its front limbs, and it has two other pairs of limbs before the largest limbs come out.

Goby Shrimp: Picture courtesy of Greg. No one was able to get a really good picture of the Goby Shrimp, and my own underwater pictures came out blurry, but I derived their characteristics from sketches and notes I made from quick glimpses of the shrimp while waiting very patiently near goby holes in the fore-reef at Gaya Island. This particular picture (bit of a stretch…but look closely) has arrows showing the shrimp antennae resting on the goby, and part of its claw. It looked much like THIS but smaller, darker, and with a more mottled pattern. I suspect it might be Alpheus bidens, since appeared to have no rostrum, but I can’t find a picture of one to compare it with.
Again, I was mostly only able to get characteristics of their patterning and claws, which were asymmetrical (indicating that it is Alpheidae), and note that it had either a very reduced or absent rostrum.
These shrimp, which belong to the family Alpheidae with other asymmetrically-clawed shrimp, practice mutualistic behavior with the Goby fish; they have very bad eyesight and rely on the Goby fish to warn them of danger using a distinctive tail movement, and in return the Goby fish stay in the holes dug out by the Goby Shrimp.

Last updated August 2008. Contact Justine at jschow88[AT]gmail.com.