Feather Star Squat Lobster

Allogalathea elegans, also known as the feather star squat lobster, crinoid squat lobster, or elegant squat lobster, is a species of squat lobster that is occasionally kept in marine aquariums. Despite its common name, it is more closely related to hermit crabs than lobsters.

Allogalathea elegans exhibits bilateral symmetry, with a droplet-shaped cephalothorax. The triangular rostrum of the animal is positioned on each side of the pedunculated eyes, with varying length and a dorsally flattened and elongated shape. The chelipeds, or first pair of legs, are equipped with pincers and are longer than the body of the animal, while the last pair of legs are reduced. The body and legs are covered with small hairs. The size of this species varies depending on sex, with females typically being larger but never exceeding 2 cm. Coloration is variable, ranging from dark red, blackish-purple, orange, to brown, often with longitudinal stripes of varying thickness, number, and tint.

Allogalathea elegans is found in tropical waters of the Indo-Pacific region, including the 🌊 Red Sea. Its range extends from the eastern coast of Africa to the 🇫🇯 Fiji Islands and from 🇯🇵 Japan to Southern 🇦🇺 Australia. It has also been recently discovered in 🇰🇷 Korean waters.

This species of squat lobster lives in commensal association with crinoids, benefiting from protection and an ideal feeding substrate. While it is capable of living without its host, its lifespan will be shorter as it lacks the protection from predators. Allogalathea elegans is typically found in shallow waters at depths ranging from 0 to 146 m.

Allogalathea elegans is a planktotrophic feeder, taking advantage of its crinoid host, which has the same diet and positions itself in optimal areas for plankton to feed.

Individuals of Allogalathea elegans can be found living alone or in large aggregations. Many exhibit a symbiotic relationship with crinoids, often feather sea stars, as a means of protection against predators such as fish. These squat lobsters are frequently observed living in close proximity to or on top of crinoids. When the opportunity arises, they engage in precopulatory rituals involving various sensory cues.

Female Allogalathea elegans are multiple spawners that produce eggs that hatch into larvae. Most females undergo three or four reproductive cycles during the breeding season. Reproductive females exhibit synchronized gonadal development and breeding synchrony.

Allogalathea elegans undergoes four zoeal stages before reaching the megalopal stage, eventually transitioning into the juvenile and adult stages. The duration of the four zoeal stages ranges from 13 to 16 days in total. Once they reach the megalopal stage, they closely resemble smaller versions of the adult stage until reaching maturity.