Description

A common, boldly patterned and readily identified shrimp, but with striking variants that may or may not be the same species. 

Carapace; On white sand the base colour is white with a brown netted pattern separated by a red border. Commonly the network is so thickened and extensive that the pattern appears to be brown with white rectangular patches. This becomes extreme in shrimps living on black sand substrates, but in any habitat each animal differs in the amount of pigment. The one constant is that, like most partner-shrimps, the pattern of two transverse white bands on the dorsum of the carapace is preserved. There is a red outlined white oval on the side of the carapace. 

The abdomen retains the white transverse bands on segments 1 and 4. Otherwise the segments each carry the same pattern of a brown network enclosing a white rectangle and a crescent mark on the lateral side. The effect differs according to the individual degree of pigmentation.

The rostrum is white but the antennae and antennules are conspicuously red. 

The Pincers are white with conspicuous dark red-black bands varying from narrow to very broad depending on degree of melanism. The two pincers are different with the larger one modified into a powerful weapon. There is often a well defined dark spot distally on the inner aspect of the major claw. 

The chelate second legs are red with white joints The walking legs are white with red band either side of the joints. 

Identifying Features 

Variants, or related shrimps

There is a beautiful dark brown form we have found at Frazer Island, Australia with the dorsal network and nipper bands densely black and the sides contrasting brown and white. The claws are brown with white tips. This variant lives in pale grey sand (usually darkly pigmented individuals occur on black sand) but in this habitat there is an abundance of dark green algae in which it hides. 

A common variant found on black sand no longer has a network pattern but is uniformly ochre with very small white rectangular patches. 

Lesser degrees of variation are common and are often seen within pairs that share a burrow. 

Similar Shrimps

None

Nomenclature

The scientific name Alpheus bellulus, Miya and Miyake 1969 has been applied to this species (Ryanskiy 2015, and virtually all published texts). 

Anker 2001 considers the name includes a species complex of three species. 

Debelius (2001) Crustacea p152 has images of a similar looking shrimp and gives the name Alpheus bellulus. Length up to 4 cm, egg-bearing (ovigerous) females up to 5 cm. Distribution Indo-West Pacific, Japan (Ryukyu Islands), South China, Thailand, Indonesia, Papua New Guinea probably Seychelles and Australia. There are at least three colour morphs of this snapping shrimp (probably closely related species). 

Ryanskiy (2016) p6. has images of a similar looking shrimp and gives the name Alpheus bellulus common name Tiger Snapping Shrimp. Length up to 5 cm. Distribution Indo-West Pacific – Red Sea, Maldives Thailand, Japan, Philippines, Indonesia, Australia. 

Humann & DeLoach (2010) p84 has images of a similar looking shrimp and gives the name Alpheus bellulus, common name Tiger Snapping Shrimp. Size to 3. 5 cm. Indo-West Pacific from Indonesia to Papua New Guinea and Australia, also Japan. Shows colour variation. 

Hayashi & Shiratori (2003) Alpheus bellulus from Japan. 

Roger Steene Colours of the Reef 2015 page 407 has a vividly marked individual on black sand labeled Alpheus bellulus. 

Pairs show some variation in colour pattern and pigmentation but not dramatic differences perhaps because the individuals in one habitat are usually all the same pattern. There is an image of such a pair in the slide show opposite.