Birgus latro

Hamasaki, Katsuyuki, Tsuru, Takuma, Sanda, Tetsuya, Fujikawa, Shunsuke, Dan, Shigeki & Kitada, Shuichi, 2017, Ontogenetic change of body color patterns in laboratory-raised juveniles of six terrestrial hermit crab species, Zootaxa 4226 (4), pp. 521-545 : 529

Birgus latro

The carapace of the first stage crab (0.88–0.96 mm SL) has a V-shaped longitudinal whitish band ( Fig. 3 A, B). The pleon has a longitudinal whitish stripe along the middle portion and transverse whitish stripes on the portion containing the future tergal plates. The gastric and intestinal portions with a brownish content are visible under the semitransparent carapace and pleon; this feature can be observed in first stage crabs of all species.

The shield of the first stage crab has faint small brownish pigments; they develop into two brownish patches at the anterior one-third of the animal and a brownish band extending from the middle margin through each side wall of the whitish/creamy shield in juveniles that have an SL of> 1 mm after one month of age ( Fig. 3 A–G, 4A–E). The shield of some individuals has a longitudinal brownish stripe at the mid-posterior portion ( Fig. 3 E, 4A, D, E). The second and third pereiopods of the first stage crabs are reddish ( Fig. 3 A). After one month of age, the pereiopods generally exhibit a whitish/creamy color, and the palm of the left cheliped (the first pereiopod) develops two longitudinal brownish bands on the middle and upper portions; the propodi and carpi of the second and third pereiopods have longitudinal brownish stripes on the upper and/or lower margins; the dactyli and meri of the pereiopods become brownish ( Fig. 3 C, E, G, 4A, C–E). The brownish color of the body parts gradually changes to purplish after nine months of age ( Fig. 4 A, C–E); purplish color of the specimens was not different from that of the live crab ( Fig. 4 D, E).

Figures

FIGURE 3. Birgus latro. A (whole animal, dorsal view), B (animal showing shield and posterior carapace, left lateral view), Y 1 (sample no. in Table 1, 0.96 mm SL, 0 months old); C (whole animal, dorsal view), D (animal showing shield, left lateral view), Y 5 (1.14 mm SL, 1 month old); E (animal showing shield, posterior carapace, and some appendages, dorsal view), F (animal showing shield, left lateral view), Y 8 (1.59 mm SL, 2 months old); G (animal showing shield, posterior carapace, and some appendages, dorsal view), Y 12 (1.77 mm SL, 3 months old).

FIGURE 4. Birgus latro. A (animal showing shield, posterior carapace, and some appendages, dorsal view), B (animal showing shield, left lateral view), Y 15 (sample no. in Table 1, 1.72 mm SL, 4 months old); C (animal showing shield, posterior carapace, and left appendages, dorsal view), Y 30 (2.21 mm SL, 9 months old); D (animal showing shield, posterior carapace, and some appendages, dorsal view), Y 33 (2.72 mm SL, 12 months old); E (live crab without a gastropod shell, dorsal view) (approximately 4.0 mm SL, 24 months old).