CRABS (BRACHYURA) OF THE GULF OF MEXICO

Crabs of the Gulf of Mexico 79
tolerated for short periods. Mahood et al., (1970) showed that temperature and
salinity tolerances were interdependent. Blue crabs are also able to tolerate low
oxygen conditions and they are occasionally found in very polluted and anoxic
waters. Along the Texas coast, blue crabs in shallow ponds on sand flats are
exposed to temperatures in excess of 40°C. during midday. These crabs have
been observed to leave the water for Salicornia patches around the pools, where
they rely on aerial respiration for 2 to 4 hours in the cooler (30 to 35°C.),
humidity-saturated environment (personal observations). Blue crabs can travel
some distance overland at night and during wet periods, again relying on aerial
respiration.
Remarks: The vast literature, much of it non-technical or of a commercial
nature, precludes anything approaching a complete bibliography on this species.
The original type for this species was obtained from the eastern coast of the
United States, a variant of the form that is more typical throughout its range.
The "typical" form, most often encountered from Florida southward, was considered
a subspecies by Rathbun (1930) and many others, C. sapidus acutidens,
so-named because of the surface features and pronounced spines, teeth, and
prominent ridges. Because the type-based form from farther north was the basis
for comparison, confusion existed for some years over the designation of a type
to replace the original, which had been lost. Williams (1974a) discusses these
variations and the nomenclatural historj^ of this crab, agreeing with Chace and
Hobbs (1969) that a variety of extreme forms exist and that they could be considered
separate species if they were considered in isolation from each other.
However, these forms are intergraded and form a continuum, without morphological,
bathymetrical, or geographical discontinuity, thus all the forms of Callinectes
sapidus are considered, at present, to represent a single species in the
process of local speciation which is still morphologically incomplete.
Recent literature compilations on this species were provided by Cronin et al.
(1957) and by Tagatz and Hall (1971). Gulf regional Hsts include Florida
(Wass, 1955; Tabb and Manning, 1961; Dragovich and Kelly, 1964; Rouse,
1970; Menzel, 1971; Lyons et al, 1971), Mississippi (Richmond, 1962; Franks
et al., 1972; Christmas and Langley, 1973), Louisiana (Behre, 1950; Darnell,
1959; Hoese and Valentine, 1972), Texas (Gunter, 1950; Lledgpeth, 1950; Hoese,
1960; Copeland, 1965; Leary, 1967; More, 1969; Copeland and Bechtel, 1974),
Mexico (Contreras, 1930; Hildebrand, 1957), and north coast of Cuba (Chace,
1940).
Hay (1905) and Churchill (1919) provided comprehensive life history studies.
Other information on ecology includes: habitat relationships in Texas (Hedgpeth,
1953; Simmons, 1957; Breuer, 1962; Fotheringham and Brunenmeister, 1975;
Trent, Pullen and Proctor, 1976), megalops ecology in Maryland (Cargo, 1960),
habitat notes in Mississippi (Franks et al., 1972; Christmas and Langley, 1973),
effects of environmental variables on juveniles (Holland, Aldrich and Strawn,
1971), larval ecology in Virginia (Sandifer, 1973), seasonal population changes
in Chesapeake Bight (Musick and McEachran, 1972), field observations of freshwater
populations (Gunter, 1938), temperature and thermal tolerance (Tagatz,
1969a), and habitats in Jamaica (Norse, 1972).