Randall's Goby

Randall's Goby (Amblyeleotris randalli) is a small shrimp goby in the family Gobiidae, one of dozens of Amblyeleotris species that form a well-known mutualistic partnership with burrowing snapping shrimp (Alpheus species). It is native to the tropical Indo-Pacific, ranging from the Red Sea and East Africa through Southeast Asia to the western Pacific, including popular dive destinations such as Indonesia, the Philippines, and Papua New Guinea. The species is a favorite subject for underwater photographers because of its bold banding and tall sail fin. It is not evaluated as threatened, though like other reef gobies it depends on healthy sand-rubble habitat adjoining coral reef. It is also commonly kept in the marine aquarium trade.

Randall's Goby is recognized by:

• Elongated, slender body up to about 7 cm, pale cream to white background
• Five or six broad reddish-orange vertical bars crossing the body and head
• A tall, sail-like first dorsal fin, bright yellow-orange with a black spot ringed in pale blue near its front edge
• Fine electric-blue spots scattered across the head and nape
• Large eyes set high on the head, typical of burrow-dwelling gobies

It closely resembles other banded Amblyeleotris shrimp gobies, but the combination of orange banding with the black-and-blue-ringed dorsal eyespot is diagnostic. Like relatives, it hovers just above its burrow entrance rather than resting flat on the substrate.

Randall's Goby lives on sand and rubble patches adjacent to coral reefs, lagoons, and sheltered slopes, typically at depths of about 5 to 35 meters in warm tropical seas. It requires open sandy substrate soft enough for its shrimp partner to excavate a shared burrow, usually near coral bommies or rubble that offers some shelter. Its range spans the Indo-West Pacific, from the Red Sea and East African coast eastward through the Indian Ocean, Southeast Asia, and into the western Pacific around Indonesia, the Philippines, Palau, and northern Australia. Water temperatures in its range generally stay between 24 and 29°C. It is rarely found far from a burrow, since the sandy flats it favors offer little cover from predators.

This goby forms a classic symbiotic pair with a burrowing snapping shrimp, most often an Alpheus species. The nearly blind shrimp digs and maintains the shared burrow while the goby, with sharper eyesight, stands guard at the entrance; both keep a tail or antenna in contact so the shrimp can flee instantly if the goby signals danger with a tail-flick. Randall's Goby feeds by hovering just above the burrow and picking passing zooplankton from the current, darting back into the tunnel when threatened. Pairs are typically monogamous and defend their burrow site against neighboring gobies. Spawning occurs within the burrow, where eggs are laid on the tunnel walls and guarded until hatching.