Florida softshell turtle
The oval carapace (to 60 cm) is gray to brown and may have darker blotches, especially in younger individuals. A series of enlarged, blunt tubercles lies along the anterior rim of the carapace and on the well-defined marginal ridge. Often there are longitudinal rows of indentations and small raised tubercles on the dorsal surface. No preneural bone is present and only a single neural bone separates the anterior pair of costals. Seven or eight neurals and seven or eight pairs of costals are present; the last pair of costals meet at the midline. Carapacial bones are strongly pitted. The gray to white plastron has hyo-hypoplastral and xiphiplastral callosities, but callosities are usually lacking or poorly developed on the epiplastra and entoplastron. The epiplastra are separated, and the entoplastron lies at right angles to the midline. Often there is no suture between the hyoplastra and hypoplastra. The moderately sized skull has a bony snout slightly longer than the diameter of the orbit. The mandibular symphysis is shorter than the diameter of the orbit. No ridge occurs on the maxillary triturating surface, and this surface may be broadened in older males. Head and limbs are gray to brown and sometimes bear light mottlings or reticulations. Often a red or yellow stripe extends from the posterior corner of the eye to the base of the lower jaw. Each nostril contains a lateral ridge that projects from the nasal septum.
The normal chromosomal complement is 66 (Becak et al., 1964; Bickham et al., 1983), consisting of 16 macrochromosomes (8 metacentric, 2 submetacentric, 4 acrocentric, 2 telocentric) and 50 microchromosomes. The karyotype is identical to that of P. sinensis and A. spinifera (Bickham et al., 1983).
Adult females are 20-60 cm in carapace length, males 15-29 cm. Males have long, thick tails with the vent near the tip. Older males may develop an expanded crushing surface in the upper jaw.
Apalone ferox ranges from southwestern South Carolina and southern Georgia southward through peninsular Florida and westward through the Florida Panhandle and southern Alabama to Mobile Bay.
This softshell occurs in all freshwater habitats, but in the northern parts of the range it seems to be more at home in still waters than in the southern part of the range. It prefers deep water with sand or mud bottoms, or bubbling mud-sand springs where there is foliage overhead. It sometimes occurs in brackish water near the mouths of streams, and the tides occasionally carry it out to sea.
Males may mature at a plastron length of 12 cm (Webb, 1962). The smallest mature females on record had carapace lengths of 22 cm (Hamilton, 1947) and 24 cm (Iverson and Moler, 1997), respectively; but Iverson (1985c) and Iverson and Moler (1997) thought that some females only reach maturity at carapace lengths of 28-30 cm. The male gametic cycle has not been described. Females from southern Floridas have follicles of ovulatory diameter in late February, and contain unshelled oviducal eggs in early March (Iverson and Moler, 1997). Iverson (1985c) reported that a female collected in late April contained oviducal eggs, 18 follicles 19-25 mm in diameter, 12 follicles 13-18 mm in diameter, and two different size classes of corpora lutea. Two other females collected in June contained 12 and 24 oviducal eggs, respectively, and two series of enlarged follicles 17-24 mm and 10-17 mm in diameter.
Nesting apparently lasts from late March to early August. A typical nest has a total depth of about 12.5 cm.
The spherical, white eggs have thin, brittle shells; they are 24.0-33.5 mm in diameter. Clutches consist of 4-38 (mean 20-21) eggs, but most commonly 17-22 eggs. Clutch size increases with an increase in female body size. Five or six clutches may be laid a year, but about 9% of mature females may not reproduce every year (Iverson and Moler, 1997). Hatching occurs in August and September, after about 60-70 days of incubation.
Hatchlings are 36.2-44.3 mm (Heinrich and Richardson, 1993) and less rounded than are those of other North American species of Apalone. The carapace is yellowish olive with dusky spots and a narrow yellow or orange border. The spots are large, and the narrow light lines separating them give a reticulated appearance. The plastron is dark gray, and the olive skin is mottled with lighter pigment. A Y-shaped figure extends from the anterior edge of each orbit to the middle of the snout.
Apalone ferox is thought to be omnivorous, but not overly fond of plant material. The bulk of the diet apparently consists of invertebrates, and the turtle is known to do some scavenging. Its natural foods include crayfish, snails, mussels, frogs, fish, and waterfowl. Captives readily feed on canned and fresh fish, canned dog food, raw beef, and chicken. The expanded crushing surface of the jaws in some large individuals may be an adaptation for crushing mollusks.
The Florida softshell spends much time buried in the soft bottom in either shallow or deep water, with only its head protruding. When buried in the mud it appears to consider itself perfectly concealed and protected. It can burrow into and tunnel through mud with amazing speed.
IUCN Red List Status (1996)