Crustacea in Bromeliads | Bromeliad Phytotelmata | Bromeliad Biota

Brachyura - crabs

Leaving the microscopical level, the crab species (Malacostraca: Grapsidae) Sesarma angustipes was found in Brazilian and Metopaulias depressus in Jamaican bromeliads (Sattler & Sattler 1965: see Abele 1972, Rathbun 1918). Diesel (1989) studied the adaptive value of parental care in females of M. depressus: The selection of a breeding site in large bromeliads, especially Aechmea paniculigera (Swartz) Grisebach, with high water reduces the risk of drying out during the development of the offspring. The removal of debris, except snail shells, accumulated in phytotelmata has a positive impact on the water chemistry with regard to oxygen content being higher and carbon dioxide concentration being lower in nursery phytotelmata than in those containing debris (Diesel 1992a). Snail shells left in phytotelmata or even transported by M. depressus into the nursery buffer the water to neutral and increase the availability of calcium needed for molt (Diesel 1989, 1992a). In addition to habitat selection and maintenance, M. depressus shows brood feeding. The crab's diet includes, among other organisms, snails, millipedes, which were ripped into pieces to feed the young, and larvae of the damselfly Diceratobasis macrogaster Selys. Predatory larvae of Diceratobasis macrogaster have a negative effect on the survival of the crab's offspring by feeding on them (Diesel 1989, 1992b). In turn, adult crabs feed on damselfly larvae, which reduces the loss of the crab's brood. In this regard, Diesel (1989, 1992b) distinguished between (1) defending the young against predators and (2) feeding them as different components of maternal care. This differentiation is supported by Diesel's observation (1989) that the spider Ctenus cf. malvernicus, another predator of juvenile crabs, was not encountered in the nursery axils even if present in the bromeliad with breeding females.

The Jamaican bromeliad-inhabiting crab Metopaulias depressus (Photo: W. Janetzky)

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Crustacea in Bromeliads
Bromeliad Phytotelmata