Thor amboinensis

Common Names: Anemone shrimp, squat shrimp, sexy shrimp, sexy anemone shrimp, high-tailed shrimp, humpback shrimp, dancing shrimp, Pikmin shrimp

Phylum: Arthropoda

Class: Malacostraca

Order: Decapoda

Family: Hippolytidae

Range: All tropical oceans; common in the Indo-Pacific from Eastern Africa to the Central Pacific Ocean, yet somewhat rare in Bermuda and the Caribbean

Natural Environment: Inhabits shallow coral reef environments receiving gentle to moderate water movement, where they are usually found living within the tentacles of various sea anemones.

Water Requirements: Calcium 380 to 430 ppm, alkalinity 2.5 meq/l, pH 8.1 to 8.2, specific gravity 1.024 to 1.026, and a temperature range of 72° to 81°F (22° to 27°C). Iodine is also believed by many to be an important factor to the molting process.

Captive Care

These small, nearly inch-long comical shrimp are commonly named the sexy shrimp because they have a tendency to vibrate their abdomen while walking. As they do so, they arch their tail upwards towards their head, often shaking the tail as if sending a signal to others of their species or as a warning to predators. They are non-aggressive shrimp that feature a caramel/brownish body decorated by large white to pinkish spots surrounded by a thin bluish circle. Their white eyes are located on the end of short stalks. They can move quickly and are capable of going short distances (about 4 to 6 inches [10 to 15 cm]) in the blink of an eye.

In the Wild

In the wild, they are found in groups between the tentacles of anemones, which protect them from predators. There is no single anemone genus/species preference that I know of, as it seems to be an individual chemical preference between the shrimp and anemones that finally dictates the symbiotic partnership. Nevertheless, in aquariums without anemones, I’ve found them highly satisfied with a relationship on various Zoanthus species.

Feeding

No direct feeding is necessary, as they appear to feed off the slime of corals in the aquarium, and Zoanthus and Euphyllia species seem to be their favorite places to group in my aquariums. It is not clear whether it’s the mucus or trapped organisms within it that they feed upon. Regardless, they will seek and feed upon meaty scraps that make it past the other animals in my aquaria.

Reproduction

In one of my smaller aquariums containing three specimens, I currently have about a hundred baby sexy shrimp of various sizes, ranging from 1/16 to ¼ inch. Therefore, there must be a mix of females and males, as these shrimp reproduce sexually. Whether or not they will reach adult size is still to be determined, however; their continued spawning has gone on for almost a year, with their larger tankmates enjoying the live plankton-like food! The information I have points to them molting almost monthly, so alkalinity and calcium levels are important water parameters.

Tankmates

Consider these shrimp reef aquarium inhabitants, and if the aquarium does not contain usable anemones, then large predators such as triggerfishes, wrasses, hawkfishes, and angelfishes do not make suitable tankmates. Clownfish would be unsuitable as well, as they would not want others being in their anemone!