Triplespot Shrimpgoby

The burrow this fish lives in is not its own. A snapping shrimp dug it, a snapping shrimp keeps it open, and the goby pays rent by standing at the door.

The partner here is Alpheus bellulus, a stout shrimp with poor eyesight that bulldozes sand out of the tunnel with its claws all day. Whenever it is outside the hole it keeps one long antenna laid across the goby's tail. The goby faces out and watches. A fast flick of that tail travels down the antenna, the shrimp reverses underground, and the fish drops in after it. Neither animal can do the other's job: the shrimp cannot see the predator, and the goby cannot dig a hole in loose sand that stays open.

The name is a counting exercise. Three black spots: one on the nape just above the gill cover, two more on the first dorsal fin. The rest of the body is whitish, crossed by reddish-brown bars with irregular brown markings between them, and a curved dark line runs from below the eye down to the upper jaw. Nine centimeters is the maximum, and most are smaller.

Look for it on sand and rubble at the foot of the reef between about 2 and 17 meters. The burrow mouth is a shallow crater with a fan of coarse sand pushed out of it. Approach head-on and slowly, stop breathing out hard, and stay low; a diver arriving from above puts both animals underground before there is anything to photograph.

Be honest about the odds. This is not the 🌊 Red Sea's usual Amblyeleotris - steinitzi and sungami are the ones most divers end up photographing. Triplespot is recorded from here east to the 🌊 Gulf of Oman and the 🌊 Persian Gulf, and the picture in the regional guide for this sea was taken in the UAE.