Reprinted from the JAMAICA NATURALIST

CITATION:

Diesel, Rudolf. A Jamaican Specialty: The Bromeliad . Jamaica Naturalist, Vol. 1, 7-9. 1991.

Published by the NATURAL HISTORY SOCIETY OF JAMAICA http://naturalhistorysocietyjamaica.org/ NHSJ

A JAMAICAN SPECIALITY: THE BROMELIAD CRAB by Rudolf Diesel

Abteilung Wickler Max-Planck-Institut fur Verhaltensphysiologie 8130 Seewiesen Federal Republic of Germany

INTRODUCTION Trelawny (altitude 90m; There is a remark­ approximate distance from the able variety of freshwater sea 30km), in 1986 and 1987. and terrestrial in This heavily eroded karst Jamaica. At least five species region consists of steep, forest­ of the family Grapsidae, all covered hills of 60 - 100 m belonging to the subfamily height near Windsor. As in Sesarminae, live in mountain most karst areas in central rivers and streams (Sesarma Jamaica rain water drains bideniaium), under stones through the porous limestone and rubble in mountain into the numerous subterra­ forests (5. iaroisi and The br orncl iad crab , Metopaulias depressus. nean cave-systems, and perma­ S. cookei), in subterranean rain­ A mother crab wi th young in the nursery. nent surface rivers are missing. (llus tration by the author) water reservoirs of brorneliads However, moisture is trapped by (Metopaulias depressus ). All these as, since Laessle's (1961) micro­ bromeliads whose leaves channel crabs live a secret life, and it-was limnological study on the bromeliad the water into the leaf axils where it not until the 1960s that Hartnol water-tanks, it has been recognized is stored. They provide the only (1964a, b, 1971) and later Abele and that this habitat is a very harsh envi­ permanent water source in these Means (1977) threw some light on ronment for crabs to breed in; it is areas. their life history. However, most of especially hostile to larvae and juve­ The associated their biology, especially the repro­ niles. From this unique ecological with bromeliads were studied in ductive behaviour has remained situation, the interesting question the Discovery Bay Marine Labora­ obscure. arose - how do brorneliad crabs tory as well as in the field . Lab The bromeliad crab, Meto­ mitigate the harshness of this environ­ specimens were recei ved by remov­ paulias depress us, is quite common, ment for their young? The bromeliad ing and dissecting several hundred although few people have ever crab promised to be one of the most plants. Field observations included seen it in the wild. Local people, exotic and exciting crabs of Jamaica, if plants growing on the ground, usually well aware of the creatures not the world. epiphytically on tree trunks, and in living in their environment, never the forest canopy. The canopy mentioned this crab when I ques­ MATERIALS AND METHODS plants' were investigated by climb­ tioned them about the animals that The bromeliad crab is the only ing up to a height of over 30m, live in "wild pines" (brorneliads). species of the Metopaulia aided by a rope and climbing It has been assumed that tmonotypic). Its carapace is nearly equipment. A number of individu­ bromeliad crabs pass their entire square, in large animals measuring 2 x ally marked crabs were observed in lifecycle in the water-tanks of bro­ 2 cm; the body is depressed, reddish­ the field for several months. Most meliads (Laessle 1961, Hartnoll brown and purple in colour and the observations were done from 1900 1964a). This is a very unsual envi­ claws are sharply pointed. It is found to 2400 hours using a battery ronment for an whose in western Jamaica, from Dolphin operated head-lamp (for more ancestors were outfitted by natural Head eastward to west of the Blue details see Diesel, 1989). selection for a marine life and Mountains. marine-planktonic larval develop­ The study was conducted in RESULTS ment. This is even more remarkable the Cockpit Country near Windsor, Crabs were most common

7 in large bromeliads, especially young from several breeding seasons (Sagda, Pleurodonia, Helicina, Neocy­ Aechmea paniculigera, and less lived in the same brorneliad, thus cloius and Trochiella), and to a lesser frequently Hohenbergia sp.iboth forming a large family group. degree beetles (Phyllophaga), moths, species are abundant on the top of Following metamorphosis termi tes and ants. fre­ the steep karst hills. In 54% of all from the larval stage, the young crabs quently foraged in the outer, older plants examined, at least one crab frequently left the water and moved leafaxils which were without was present. Adults usually along its edge. Like adults they are water. They were also found to inhabited the largest bromeliads, able to breathe in air as long as they breed in these axils. preferably A. paniculigera which maintain a thin film of water circulat­ Field.observations revealed sometimes contained more than ing between the outer parts of their that the bromeliad crab subsists 3.5 liters of water. Bromeliads body surface and gills. predominantly on invertebrate growing on the ground had the The young were usually prey, rather than plant matter. highest number of crabs, but found grouped around the mother in While hunting, adult crabs visited breeding females were also found one comer of the nursery axil. Some­ several leafaxils on their "home"­ in plants on tree trunks and up to times, they climbed on her body and plant. Occasionally they were 20m above the ground, in the were observed feeding from her found standing upright with raised, canopy. The breeding activities carapace surface in several instances. open claws at the edge of the water, started before the spring rainy sea­ While shooting close-ups of crab apparently waiting for prey. In son, in the latter part of January to families in the lab, James Cray of a several cases, I offered hunting mid February. A second breeding BBCfilm team, observed that the crabs invertebrate prey items. season appeared to start in the young fed around the mouthparts of These were immediately caught, latter part of September to late their mother. pulled under the surface of the October, as already suggested by During the first two months of water and killed . On one occasion, Hartnoll (1964a). Each reproduc­ juvenile development, the mother was a crab attacked a 'fortyleg' (centi­ tively active female spawned 20 to usually found in the nursery, guard­ pede) of 12 ern length which I 100 relatively large eggs (1.5 nun ing the young against predators. The dropped into an axil; the crab in diameter) and incubated them most common predator was a large killed its much larger victim after a attached to her abdominal append­ nocturnal spider (Ctenu s maluernenis ) period of wrestling. ages. which hunts on bromeliads and has After approximately 12 been observed catching a juvenile crab DISCUSSION weeks of development, larvae in three cases. In field experiments, I The Jamaican bromeliad were released into the water of a have removed mothers from their crab has one of the most thrilling single, large leaf axil - usually on brood, thus leaving the young without natural histories. Supris­ the outer and lower side of a bro­ care and protection. This led to a ingly, it is the only crab which uses meliad. However, before releasing decrease in juvenile survival. The bromeliads for breeding, although the eggs, mother crab prepared the result dearly demonstrated the signifi­ such plants are common on other leaf axil by removing accumulated cance of maternal care for the young. Caribbean islands as well as in leaf litter and organic detritus. A large number of young live Central and South America. Species This clean-out behaviour probably in the limited space within a leaf axil, of the genus Sesarma, a genus which improved the condition of the though practically no food resources contains the closest relatives of the water for the larvae which were are present. I could not solve this bromeliad crab, are very common released from the eggs. The juve­ mystery until I observed a crab mother in tropical and subtropical fresh niles were dark-pigmented and de­ carrying a across several waters and terrestrial habitats. Oc­ veloped rapidly; they molted into leaves into the nursery. There she cut casionally, adults of some species young crabs within only nine days the prey into pieces and deposited like S. angustipes are found in bra­ (Hartnoll, 1964a). The young them at the edge of the water, where meliads near to the sea (Abele 1972 remained in the nursery for ap­ later, the young started feeding on a, b; personal observations in proximately 8 weeks. Thereafter, them. Subsequently, I repeatedly ob­ Panama) but do not breed there. they dispersed to neighbouring served females hunting along the This conclusion arises from the fact leafaxils, but stayed on their surface of the bromeliad leaves. The that S. angustipes females produce "home" - plant for up to a year. In most common prey were millipedes several thousand small eggs, an many cases, a mother and her iSpirobolida, Polydesmidae) and snails attribute of those species which

8 have marine-planktonic larvae. Pre­ ground provided water and a rich REFERENCES sumably, the crab is partly terrestrial source of-food, permitting a long and only visits bromeliad water­ sojourn and even offering the neces­ Abele, L.G. 1972a. A note on tanks to moisten the gills or to search sary medium in which to breed. the Brasilian bromeliad crabs (Crustacea, Grapsidae). Arq. Cien. for food. Today we find the related Nar. ( Fortaleza) 12: 123-126. The question remains: why species Sesarma iaruisiliving in a ter­ is it that crabs breeding in bromeli­ restrial habitat in the same area as 1972b. The status of Sesarma ads have evolved only in Jamaica? M. depress us. S. jarvisiis apparently angusiipes Dana, 1852; Sesarma trape­ I suggest a combination of two eco­ more independent of water for respi­ zium Dana, 1852 and Sesarma miersie Rathbun, 1897 (Crustacea, , logical patterns unique to the island : ration than M. depress us, but still re­ Grapsidae) in the western Atlantic. quires water in which to molt. I Carib. J. Sci. 12: 1. There are two major groups observed S. [aroisi molting in rock 165-170. of crabs comprising many species holes which contained a littl~ water that have evolved independence in after rain. In a few cases they were and D. B. Means 1977. their larval development from the found to molt in the water of brome­ Sesarma jarvisi and Sesarma cookei: montane, terrestrial crabs in Jamaica sea: the Potamoidea and the liads . In terms of history, the ances­ (Decapoda). Crusiaceana 32: 93-99. Sesarminae: Both are widespread tors of S.[aroisi may also have in tropical and subtropical areas, and separated from a fresh water species both compete for the same habitat. and adapted to a completely terres­ Diesell, R. 1989. Parental Jamaica differs from other Caribbean trial life at an epoch when the bro­ care in an unusual environment: Metopaulias depressus (Decapoda: islands and Central and South Amer­ meliads had already been occupied Grapsidae), a crab that lives in ica by lacking-representatives of the by the larger and stronger progeni­ epiphytic bromeliads. Anim. Behav. Poiamoidea. Hartnell (1964a)sug­ tors of M. depressus. 38: 561-575. gested that this absence led to an Only further studies of the extended spread of sesarrnid crabs. relationship of Jamaican Sesarminae and the detailed knowledge of their HartnoIl, R. G. 1964a. The I freshwater grapsid crabs of Jamaica. 2. Bromeliads provide a per­ biology will throw more light on the Proc. Zoo1. Soc. London 175: 145-169. manent, and in many parts of the evolutionary events which took island including most limestone .p lace. 1964b. Two cavernicolous areas, the only permanent freshwater decapods from Jamaica. Crustaceana reservoir. In addition, bromeliad di­ 7. versity is extremely high in Jamaica 1971. Sesarma cookei n. sp., with more than 60 species of which a grapsid crab from Jamaica (Deca­ at least 40 are endemic to the island . poda, 13rachyura). Crusta.ceana 20: Plants of numerous large species 257-262. belonging to the genera Aechmea, ACKNOWLEDGEMENTS Hohenbergia, Tillandsia, Guzmania, Laessle, A.M. 1961. Micro­ Vriesia and Piicairnia can store I thank Jeremy Woodley for limnological study of Jamaican several liters of water. his hospitality at the Discovery Bay bromeliads. Ecology 42: 499-517. The ancestor of Metopaulias Marine Laboratory, Marion Brand­ depress us may have been species hoff, Gunter Diesel, Ariel Fuchs and living near streams or rivers, inde­ Ernst Natt for their valuable help in pendent of the sea and with an ab­ the field. My very special thanks breviated larval development, but goes to Richard Campbell of Wind­ dependent on freshwater for breed­ sor, Trelawny, for his infinite help, ing. This species may have visited his generous hospitality and friend­ nearby areas in order to search for ship. food. However, the need for water to moisten the gills required frequent visits to fresh water resources, no matter how small they may have been. Brorneliads growing on the

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