Rostrum clearly longer and slightly narrower than orbital processes, not depressed, without ridge running on to carapace; very shallow grooves between. Orbitorostral process present. Large claw (chela) swollen, upper margin of sixth segment (propodus) ending in variable projection. Small claw (chela) fingers simple, each with simple apex. Fourth segment (merus) of third leg (pereopod 3) without spiniform setae on lower margin, no distal tooth; last segment (dactylus) with 2 distal claws, upper one longer than lower. Tailfan (telson) with stout dorsolateral spiniform setae. Maxilliped 3 with circlet of short apical spiniform setae and setae on inner face of terminal article. Up to 2.5 cm long.
The species is often found in male-female pairs and sometimes in larger numbers inside sponges. The fingers at the end of the larger claw are used to make a loud snapping noise to stun prey. Some species of Synalpheus are reported to have a simple sort of social behaviour and have been likened in this way to bees and ants.
In algae, coral and sponges, to 150 m depth.
Circum-Australian and Indo-Pacific Oceans.
Recorded in Australia
- DSE Advisory List : Not listed
- EPBC Act 1999 : Not listed
- IUCN Red List : Not listed