Galathea intermedia is common, but cryptic, on Clyde maerl deposits where it lives in small groups of mixed sex and age, sharing shelters (typically dead Dosinia shells) to avoid predation. Its appearance is marked by six iridescent blue spots which may play an important role in intra- or interspecific interactions

Hall-Spencer, JM

Moore, PG

Sneddon, LU

Journal of the Marine Biological Association of the United Kingdom

English

Galathea intermedia is common, but cryptic, on Clyde maerl deposits where it lives in small groups of mixed sex and age, sharing shelters (typically dead Dosinia shells) to avoid predation. Its appearance is marked by six iridescent blue spots which may play an important role in intra- or interspecific interactions.</jats:p

J.M. Hall-Spencer

P.G. Moore

L.U. Sneddon

Crossref

Observations and possible function of the striking anterior coloration pattern of <i>Galathea intermedia</i> (Crustacea: Decapoda: Anomura)

Hall-Spencer, J. M.

Moore, P. G.

Sneddon, L. U.

WBI Studies Repository (WellBeing International)

WellBeing International WBI Studies Repository 4-1999 Observations and Possible Function of the Striking Anterior Coloration Pattern of Galathea intermedia (Crustacea: Decapoda: Anomura) J. M. Hall-Spencer University of Glasgow P. G. Moore University of Glasgow L. U. Sneddon University of Glasgow Follow this and additional works at: https://www.wellbeingintlstudiesrepository.org/acwp_vsm  Part of the Animal Structures Commons, Animal Studies Commons, and the Other Animal Sciences Commons Recommended Citation Hall-Spencer, J. M., Moore, P. G., & Sneddon, L. U. (1999). Observations and possible function of the striking anterior coloration pattern of Galathea intermedia (Crustacea: Decapoda: Anomura). Journal of the Marine Biological Association of the UK, 79(02), 371-372. This material is brought to you for free and open access by WellBeing International. It has been accepted for inclusion by an authorized administrator of the WBI Studies Repository. For more information, please contact wbisr-info@wellbeingintl.org. Observations and Possible Function of the Striking Anterior Coloration Pattern of Galathea intermedia (Crustacea: Decapoda: Anomura)  J.M. Hall-Spencer, P.G. Moore and L.U. Sneddon University of Glasgow  Galathea intermedia is common, but cryptic, on Clyde maerl deposits where it lives in small groups of mixed sex and age, sharing shelters (typically dead Dosinia shells) to avoid predation. Its appearance is marked by six iridescent blue spots which may play an important role in intra- or interspecific interactions.  Anomuran decapod crustaceans of the genus Galathea are widespread in rocky/gravelly subtidal areas around north-western European coasts (Zariquiey Alvarez, 1968). Recent interest in the group has been stimulated by the growing commercial importance of squat lobsters as the target of an expanding European fishery. However, the biology and ecology of these animals remain poorly studied (De Grave & Turner, 1997). Of the six species of Galathea known to occur in coastal waters (to 200m) around the British Isles (Howson & Picton, 1997), five have been recorded in the Clyde Sea area (Allen, 1967). Our attention was drawn to Galathea intermedia Liljeborg, the smallest of these species (carapace length       < 8.5mm), during in situ observations between 6 and 15m depth on two maerl grounds in the Clyde Sea (Stravanan Bay 55˚45.3301′N 05˚4.2601’W and Creag Gobhainn 56˚00.6001’N 05˚22.2000’W) using SCUBA. Galathea intermedia were found in small groups, hiding in the interstices of maerl fragments or with up to three animals sharing the shelter of dead Dosinia exoleta (L.) shells. These bivalve shells were common on the sediment surface of the study sites having fallen prey to the starfish Marthasterias glacialis (L.) and Asterias rubens L. (J.M.H.-S., personal observation). A previously unrecorded feature of G. intermedia is its very conspicuous anterior coloration pattern consisting of six `neon' blue spots in the frontal region of the head (a triangular epistomial patch medially above a small labral spot, a pair of lateral spots beneath the eyes at the base of the antennae and a pair of spots on the geniculate carpopodite of the second maxilliped endopodite).  Observations on the incidence of this coloration were made on 86 G. intermedia, with carapace lengths from 3.4 to 7.9mm, measured from the tip of the rostrum to the posterior mid-dorsal margin. These animals were collected by removing maerl sediment and dead Dosinia shells from a 5m2 area at 10m depth in Stravanan Bay on 25 September 1997. The squat lobsters clung to the collected substratum and few escaped. Previous UK records of G. intermedia show that it can be very common on gravelly sediments in the shallow sublittoral, with few records beyond 50m depth (Marine Biological Association, 1957; Bruce et al., 1963; Crothers, 1966; Allen, 1967). The population density of G. intermedia recorded here on coralline gravel (at least 17ind m-2) is within the range of 3.0-16.6 ind per 0.25m-2 encountered by Samuelsen (1970) at a similar depth (7-9m) in Norway. He also found that this species was contiguously distributed with its abundance being positively correlated with the amount of coarse substratum. When placed in aquaria, the squat lobsters hid amongst the shell/maerl substrata. Animals of various sizes settled near to one another with equanimity and began a routine of feeding and self-grooming (recorded using a Panasonic F10 video-camera (film rate 25 fields s-1) fitted with a 50mm Pentax macro-lens and connected to a Panasonic AG6200 video-recorder). The bright blue iridescent markings were strikingly apparent in en face view (Figure 1A). The largest and most conspicuous markings (visible in situ to the naked eye of divers) were on the carpopodite of the second maxilliped endopodite above due to limb flexure, but anatomically below a contrasting red/brown patch on the propodite (Figure 1A,B). These features are lost when the animals are fixed in alcohol or formalin, which probably explains why they have been overlooked in previous descriptions of the species (e.g. Liljeborg, 1851; Bouvier, 1940; Zariquiey Alvarez, 1968). The spacing and size of the markings increased with size of the animal but there were no obvious differences in their pattern or intensity depending upon the sex, maturity or egg-bearing status of individuals as this configuration of markings was present on all collected specimens. A few individuals moulted in captivity and the markings were seen before and after ecdysis. Figure 1. Galathea intermedia: (A) en face view (posterior thoracic limbs and abdomen excluded) with iridescent blue patches numbered 1 to 6; (B) left maxilliped 2 with brown (cross-hatched) and blue (stippled) patches indicated. Scale bars: 1mm.   Filmed observations in aquaria showed that G. intermedia used its chelae to tear food when presented with scraps of crab flesh but that scavenging was not its normal feeding mode, as shown with G. squamifera Leach, G. strigosa (L.) and G. dispersa Bate (Nicol, 1933). The ability of G. intermedia to detect carrion appeared to be limited, as scraps were ignored if lying beyond two body lengths from the animal. The animals fed primarily on detritus, sweeping fine particles from the substratum using the setose third maxillipeds and passing material on to the second maxilliped and thence to the mandibles. The highly reflective spots on the second maxilliped endopodites moved constantly as the animals fed or groomed the head region, this movement ceased when animals were disturbed with forceps and when conspecifics met. Given the shallow-water and contagious distribution of G. intermedia, the highly reflective blue spots may have a function in communication. Their pattern and colour (or contrast in colour) may provide a means of intraspecific recognition ensuring that shelters are only shared with conspecifics. Vannini & Gherardi (1981) demonstrated individual recognition in crabs and several studies have shown that markings in£uence interactions between crustaceans (e.g. patches on hermit crab claws, Dunham, 1978; meral spots in stomatopods, Hazlett, 1979). The distance between the spots may indicate size of an individual and therefore be important in agonistic interactions, where obtaining information on an opponent may influence whether to engage an opponent; and in affecting the outcome of a fight (Parker, 1974). In the hermit crab, Calcinus laevimanus (Randall), the size of the white patch on the enlarged left chela influenced the likelihood of winning a fight with crabs being more successful if they had a larger patch than their opponent (Dunham, 1978). Alternatively, these morphological traits may deter visual predators or play a role in sexual selection (see Kodric-Brown & Brown, 1984). These preliminary observations have highlighted the need for more detailed behavioural study to elicit the function of these brightly coloured markings. Experimental investigation into the arrangement, colour, size and intensity of these spots and the role they play in communication (analogous to Crane's work (1949) on salticid spiders) would be of great interest.   This study was made within the framework of the BIO-MAERL project with financial support from the European Commission's Marine Science and Technology Programme (MAST III) under contract MAS3-CT95-0020. Professor J. Davenport and Dr R.J.A. Atkinson helped with video techniques, Mr K.S. Cameron and Mr H. Brown provided diving assistance.  REFERENCES Allen, J.A., 1967. The fauna of the Clyde Sea area. Crustacea: Euphausiacea and Decapoda. Millport: Scottish Marine Biological Association. Bouvier, E.L., 1940. Décapodes marcheurs. Faune de France, 37, 1-404. Bruce, J.R., Colman, J.S. & Jones, N.S., 1963. Marine fauna of the Isle of Man and its surrounding seas. Liverpool: Liverpool University Press. Crane, J., 1949. Comparative biology of salticid spiders at Rancho Grande, Venezuela. Part IV. An analysis of display. Zoologica, 34, 159-214. Crothers, J.H., 1966. Dale Fort marine fauna. Shrewsbury: Field Studies Council Publications. De Grave, S. & Turner, J.R., 1997. Activity rhythms in the squat lobsters, Galathea squamifera and G. strigosa (Crustacea: Decapoda: Anomura) in south-west Ireland. Journal of the Marine Biological Association of the United Kingdom, 77, 273-276. Dunham, D.W., 1978. Effect of chela white on agonistic success in a diogenid hermit crab. Marine Behaviour and Physiology, 5, 137-144. Hazlett, B.A, 1979. The meral spot of Gonodactylus oerstedii Hansen as a visual stimulus. Crustaceana, 36, 196-198. Howson, C.M. & Picton, B.E., ed., 1997.The species directory of the marine fauna and flora of the British Isles and surrounding seas. Belfast: Ulster Museum. Ross-on-Wye: The Marine Conservation Society. Kodric-Brown, A. & Brown J.H., 1984. Truth in advertizing: the kinds of traits favored by sexual selection. American Naturalist, 124, 305-322. Liljeborg, W., 1851. Norges Crustacér. Öfversigt af Kongl. Vetenskaps-Akademiens Förhandlingar, Stockholm, 8, 19-25. Marine Biological Association, 1957. Plymouth marine fauna. Plymouth: Marine Biological Association. Nicol, E.A.T., 1933. The feeding habits of the Galatheidea. Journal of the Marine Biological Association of the United Kingdom, 18, 87-106. Parker, G.A., 1974. Assessment strategy and the evolution of fighting behaviour. Journal of Theoretical Biology, 47, 223-243. Samuelsen, T.J., 1970. The biology of six species of Anomura (Crustacea, Decapoda) from Raunefjorden, western Norway. Sarsia, 45, 25-52. Vannini, M. & Gherardi, F., 1981. Dominance and individual recognition in Potamon fluviatile: possible roles of visual cues. Marine Behaviour and Physiology, 8, 13-20. Zariquiey Alvarez, R., 1968. Crustáceos Decápodos Ibéricos. Investigación Pesquera. Barcelona, 32, 1-510. 

Observations and Possible Function of the Striking Anterior Coloration Pattern of Galathea intermedia (Crustacea: Decapoda: Anomura)

Humane Society Institute for Science and Policy

PEARL (Univ. of Plymouth)

Observations and possible function of the striking anterior coloration pattern of \u3ci\u3eGalathea intermedia\u3c/i\u3e (Crustacea: Decapoda: Anomura)

1851. Norges Crustace ¨ er. Úfversigt af Kongl. Vetenskaps-Akademiens FÎrhandlingar,

1997.The species directory of the marine fauna and £ora of the British Isles and surrounding seas. Belfast: Ulster Museum. Ross-on-Wye: The Marine Conservation Society.

Activity rhythms in the squat lobsters, Galathea squamifera and G. strigosa (Crustacea: Decapoda: Anomura) in south-west Ireland.

Assessment strategy and the evolution of ¢ghting behaviour.

Comparative biology of salticid spiders at Rancho Grande, Venezuela. Part IV . An analysis of display.

Dale Fort marine fauna.

De ¨ capodes marcheurs.

Dominance and individual recognition in Potamon £uviatile: possible roles of visual cues.

E¡ect of chela white on agonistic success in a diogenid hermit crab.

Marine fauna of the Isle of Man and its surrounding seas. Liverpool:

Plymouth marine fauna.

The biology of six species of Anomura (Crustacea, Decapoda) from Raunefjorden,

The fauna of the Clyde Sea area.

The feeding habits of the Galatheidea.

The meral spot of Gonodactylus oerstedii Hansen as a visual stimulus.

Truth in advertizing: the kinds of traits favored by sexual selection.

https://pearl.plymouth.ac.uk/context/bms-research/article/1375/viewcontent/Hall_Spencer_20Moore_20Sneddon_201999.pdf

Observations and possible function of the striking anterior coloration pattern of Galathea intermedia (Crustacea: Decapoda: Anomura)

Observations and possible function of the striking anterior coloration pattern of Galathea intermedia (Crustacea: Decapoda: Anomura)

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