Thymops

Lore & Background

Thymops birsteini resembles a typical lobster, with two large claws, four other pairs of pereiopods, and a long pleon. The carapace is granular, especially in the front half, and bears a rostrum that divides into two points at its tip. Smaller individuals are found in shallower waters, while larger ones occur at greater depths, up to 1400 m. There is latitudinal variation in colour: northern individuals are pale yellow, while those from further south are maroon.

The species lives on muddy bottoms and has been observed entering and exiting burrows. Little is known about its biological interactions, though it is occasionally eaten by the Patagonian toothfish Dissostichus eleginoides. As in other pleocyemates, the female broods eggs on her pleopods; one female may carry up to 380 eggs. The eggs grow during development, and newly hatched larvae have a carapace length of 1.7–2.2 mm. Extended larval release, with a maximum of 43 larvae observed on a single female, is an adaptation to low temperature, long brooding time, and low overall fecundity.

Reader's Guide

Thymops is notable as a monotypic genus whose sole species, the Patagonian lobsterette, occupies a broad depth range from 120 to 1500 m across the southern South American continental shelf. Its distribution extends from Uruguay in the Atlantic to the Antarctic Peninsula region, including the Falkland Islands and South Georgia. The species shows size and colour variation with depth and latitude: larger individuals inhabit deeper waters, and northern specimens are pale yellow while southern ones are maroon. The meat is reported to be excellent, and the species is thought to be potentially commercially exploitable if sufficient concentrations are found. Average weight of a caught individual is about 150 g, with 30% (45 g) being the meaty tail, and daily yields of 19 kg are typical. The life cycle includes egg brooding and extended larval release, an adaptation to the cold sub-Antarctic environment. Despite its potential, little is known about its ecology or population densities.

Did You Know?

• Thymops birsteini is the only species in the genus Thymops.
• Its colour varies from pale yellow in the north to maroon in the south.
• Females may carry up to 380 eggs, each 1.5–1.9 mm in diameter.