Posted by: genghisprawn | December 17, 2008

Giant Prawns of the Underworld

Shown here (photo courtesy of Jack Trout) is a Macrobrachium carcinus exuvium recovered from a cave in Belize.

Holthuis (1986) has the score, mostly — Belize is news to him:

Macrobrachium carcinus (Linnaeus, 1758). St. Augustine and Silver Springs, Florida, U.S.A. (in pools fed by subterranean water); Chiapas, Mexico; La Cueva Chica, San Luis Potosi, Mexico; Jamaica. Hobbs, Hobbs & Daniel, 1977: 148, 149, 150. — El Convento Cave, Puerto Rico. Nicholas, 1974, Int. Journ. Speleol, 6: 111.

Though it lacks explicit subterranean adaptations, M. carcinus is a well-known trogloxene (Hobbs incorrectly refers to it as a troglophile, but larval requirements for saltwater leave it unable to complete its life cycle in caves).

Now, the leap to cave-dwelling isn’t as daunting as you might think.  From what I’ve seen in El Verde, Puerto Rico, San Marcos, Texas, and the aquaria in my basement, this species is rather nocturnal to begin with … though captive specimens will quickly learn to associate your presence with food at any time of day.  Dr. Alan Covich (University of Georgia) describes going out at night to the mountain streams of El Yunque (formerly the Caribbean National Forest), where he observed Puerto Rican M. carcinus plucking smaller shrimp from the water column to pop into their mandibles like so many Fritos.  Illuminated in his flashlight beam, they’d continue grabbing at passers-by for several seconds before coming to their senses and darting out of sight with a flick of the tail.  Chemosensory antennae are clearly a good stand-in for eyes in near or total darkness.

Compared to surface water, caves also tend to have lower predation pressure, making them especially fine real estate for juveniles and adults preparing to molt.  Prior to shedding, shrimp actively seek out dark and cozy crevices in rock piles and undercut banks; it’s not unreasonable to think that our Belizean friend made his descent into darkness with a similar aim.  Then again, the specimen in question could just as well have been a long-term resident, its ink serenity broken only by glowworms and the fleeting glare of tourist headlamps.

M. carcinus is far from atypical.  Holthuis documented 12 species of Macrobrachium in subterranean waters, all of which were otherwise epigean forms.  However, several true stygobites have since been discovered, and many other species could easily be facultative cave-dwellers, the real number is probably much higher.

Macrobrachium poeti, from Java’s Gunung Sewu karst (photo by Cahyo Rahmadi).

Li et al., in their description of Macrobrachium lingyunense Li, 2006, from the Lingyun karst of Guangxi, China, summed things up pretty well:

Holthuis (1986) listed six troglobitic Macrobrachium species i.e., M. cavernicola (Kemp, 1924), M. villalobosi Hobbs, 1973, M. lucifugum Holthuis, 1974, M. acherontium Holthuis, 1977, M. microps Holthuis, 1978 and M. poeti Holthuis, 1984.  Chong (1989) described M. gua from Sabah, Malaysia, Hobbs & Hobbs (1995) described M. catonium from Middle America, and Komai & Fujita (2005) recently reported another new troglobitic species, M. miyakoense from the Ryukyu Islands, Japan, bringing to a total of nine troglobitic species.

[genghisprawn: eleven with M. lingyunense Li, 2006, and M. sbordonii Mejía-Ortíz, described in 2006 from Chiapas, Mexico]

macrobrachium-lingyunense2Macrobrachium lingyunense, from the Lingyun karst of Guangxi, China, caught and photographed by Arthur Clark.

In total, Hobbs documented 81 decapod crustacean troglobites and 58 other cavernicoles in subterranean waters ranging from springs to anchialine caves and blue holes in North and Central America, the Caribbean, and North Atlantic islands.  Of these, 36 were shrimps “(1 procarid, 11 atyids, 2 agostocarids, 15 palaemonids, 2 alpheids, 5 hippolytids),” 35 were cambarid crayfishes, and 10 were crabs “(1 grapsid, 7 pseudothelphusids, 2 trichodactylids)”.


Chong, S.S.C. (1989). A new species of freshwater prawn, Macrobrachium gua sp. nov. (Decapoda, Caridea, Palaemonidae) from Sabah, East Malaysia, Borneo. Crustaceana, 56(1): 31-38, Figs. 1, 2.

Hobbs, H.H. (1973). Two new troglobitic shrimps (Decapoda: Alpheidae and Palaemonidae) from Oaxaca, Mexico. Association of Mexican Cave Studies, Bulletin 5: 73-80, Figs. 1-3.

Hobbs, H.H. III (1994). Biogeography of subterranean decapods in North and Central America and the Caribbean region (Caridea, Astacidea, Brachyura). Hydrobiologia 287: 95-104.

Hobbs, H.H. III & H.H. Hobbs, Jr. (1995). Macrobrachium catonium, a new species of troglobitic shrimp from the Cayo Dstrict of Belize (Crustaceana: Decapoda: Palaemonidae). Proceedings of the Biological Society of Washington, 108(1): 50-53, Fig. 1.

Holthuis, L.B. (1974). Subterranean Crustacea Decapoda Macrura collected by Mr. L. Botosaneanu during the 1973 Cuban-Rumanian Biospeleological Expedition to Cuba. International Journal of Speleology, 6: 231-242, Figs. 1-3.

Holthuis, L.B. (1977). Cave shrimps (Crustacea, Decapoda, Natantia) from Mexico—Subterranean fauna of Mexico. Part III. Futher results Italian zoological mission to Mexico, sponsored by the National Academy of Lincei (1973 and 1975). Problemi attuali di Scienze e di Cultura, Accademia nazionale dei Lincei, 171(3) : 173-195, Figs. 1-8.

Holthuis, L.B., 1978. Zoological results of the British speleological expedition to Papua new Guinea 1975. 7. Cavernicolous shrimps (Crustacea, Decapoda, Natantia) from New Ireland and the Philippines. Zoologische Mededelingen, 53(19): 209-224, Figs. 1-6.

Holthuis, L.B. (1986). Decapoda. In: Botosaneanu, L. (ed.) Stygofauna Mundi. A faunistic, distributional and ecological synthesis of the world fauna inhabiting subterranean waters (including the marine interstitial). Leiden: E.J. Brill. Pp. 589-615.

Kemp, S., 1924. Crustacea Decapoda of the Siju Cave, Garo Hills, Assam. Records of Indian Museum, 26: 42-48, Figs. 1-5.

Komai, T. & Y. Fujita (2005). A new stygiobiont species of Macrobrachium (Crustacea: Decapoda: Caridea: Palaemonidae) from an anchialine cave on Miyako Island, Ryukyu Islands, Zootaxa, 1021: 13-27.

Li, J., Cai, Y., Clarke, A. (2006). A new species of troglobitic freshwater prawn of the genus Macrobrachium from Southern China (Crustacea: Decapoda: Palaemonidae). Raffles Bulletin of Biology 54(2): 277-282.

Mejía-Ortíz, L., Baldari, F., & López-Mejía, M. (2006). Macrobrachium sbordonii (Decapoda: Palaemonidae), a new stygobitic species of freshwater prawn from Chiapas Mexico. Zootaxa 1814: 49-57.


  1. Narrow in focus, yes, but I have managed to remain unpricked

  2. Dear Sirs,
    I have stumbled across your website where I have found a photograph [Macrobrachium poeti, from Java’s Gunung Sewu karst (photo by Cahyo Rahmadi)] which intrigues me.
    Our team working in Eastern Herzegovina regularly comes across great numbers of cave shrimps, such as Troglocaris ssp., most of which show a similar yellow colouring under the carapace.
    My question is simple: do you have any notion of what causes the yellow colour?
    We would be very grateful for any guidance you could provide.

    With best regards,
    Brian Lewarne.

  3. My Macrobrachium yellow.
    Selection form.

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