Bigclaw Snapping Shrimp
Alpheus heterochaelis
Description 3
Alpheus heterochaelis, the bigclaw snapping shrimp, belongs to the snapping shrimp or pistol shrimp family (Alpheidae), whose members possess a single, large chela (claw) that has been modified such that it is capable of producing a distinct snapping or popping sound. The acoustic claw snap of Alpheus heterochaelis is important as a means of stuning/killing prey, in defense, and as part of a theat display in agonistic intraspecific encounters as well (Herberholz and Schmitz 1998)Individuals are typically dark translucent green with orange and blue tipped uropods. The rostrum is small and the carapace edge is smooth and spineless and large snapping claw is strongly notched on both the upper and lower margins at the base of the fingers. The snapping claw can be either the left or right claw, and it attains a length nearly half that of the body. The opposite paired claw remains an unmodified pincer. The snapping claws of male A. heterochaelis are larger and broader than those of females of equal size (Nolan and Salmon 1970, Herberholz and Schmitz 1998).A. heterochaelis is the largest and most colorful of the snapping shrimps of the southeastern United States (Rupert and Fox 1988).Sound-production in Alpheus heterochaelis had long been believed to be the result of either rapid closure of the oversized pistol claw or of the separation of two smooth disk areas at the base of each of the fingers of the large claw. The true basis for snapping shrimp sound production was described in 2000 by Versluis et al. The authors explain that the very rapid claw closure emits a high-velocity (25m/s) jet of water whose speed exceeds cavitation conditions to create a small (expanding from miscroscopic to around 3.5mm at maximum size), extremely short-lived cavitation bubble. High-speed imaging revealed that the characteristic popping sound was actually produced by the rapid (<300 ¦#181;s after formation), violent collapse of the cavitation bubble.Lohse et al. (2001) studied this phenomenon further and found that as the snapping claw cavition bubble collapses a very short, intense flash of light is emitted. The authors conclude from this observation that the collapsing bubbles experiences extremely high internal pressures and temperatures exceeding 5,000°C.Curiously, auditory organs have not been identified in A. heterochaelis and may be absent. Mechanoreception and chemosensory reception may therefore be the most important means for individuals to analyze signals from conspecifics (Herberholz and Schmitz 1998). This subject is taken up in more detail below.
Distribution 4
Distribution of subprovince extends northward of the Carolinian subprovince of Cape Hatteras through Florida
Size 5
Adult Alpheus heterochaelis may reach a length of between 3.0 and 5.5 cm (Kaplan 1988), but individuals encountered are often considerably smaller, e.g., 6-20 mm carapace length (Nolan and Salmon 1970).
Reproduction 6
Like most other alpheid shrimp, Alpheus heterochaelis individuals are most often encountered as mated pairs and social monogamy appears to be a widespread phenomenon. A study by Rahman et al. (2003) suggests that mate guarding by the male appears to be the key factor leading to social monogamy in A. heterochaelis, i.e., rather than shared territoriality or biparental care of young. The authors indicate that the female molt cycle is highly cryptic and that females are only receptive for a few hours immediately after molting. Mate guarding through male-female pairing is therefore advantageous to the male because it maximizes mating opportunities and also to the female because it minimizes the need to search for a mate during the vulnerable soft-bodied receptive phase.Nolan and Salmon (1970) indicate that A. heterochaelis collected in their study were most often (~65% of animals collected) captured as male-femalel pairs and that such pairs could be found at all times during the study (April-August). Individuals in the majority of pairs collected from the field differed by 2 mm or less in carapace length, with a non-significant trend for females to be slightly larger than males.Male-female interactions under laboratory conditions begin similar to same sex agonistic interactions (see below). In a nontrivial number of instances, however, aggressive face-off and antennulation between a male and female gave way to mutual aquiescence and pair formation, typically in under an hour. Nolan and Salmon (1970) noted that the mechanisms underlying sexual discrimination had yet to be elucidated, but predicted that chemical cues played a role. In earlier experiments conducted by Hazlett and Winn (1962), exposure to extract from crushed shrimp of the opposite sex elicited a less aggressive response than did extracts from individuals of the same sex.
Link to Access Genomic Data 7
http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=195665&lvl=0
Sources and Credits
- (c) matbio, all rights reserved
- (c) Ernst Mayr Library, some rights reserved (CC BY-NC-SA), http://farm8.staticflickr.com/7403/8725406751_eec634426c_o.jpg
- (c) Smithsonian Marine Station at Fort Pierce, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/11525517
- (c) WoRMS for SMEBD, some rights reserved (CC BY), http://eol.org/data_objects/28471142
- (c) Smithsonian Marine Station at Fort Pierce, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/11525523
- Adapted by matbio from a work by (c) Smithsonian Marine Station at Fort Pierce, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/11525522
- (c) Emily Rose Sharkey, all rights reserved
