Violet Snapping Shrimp
Alpheus fenneri
Violet Snapping Shrimp
Alpheus fenneri
Bruce, 1994
Description
A large shrimp, growing up to 12 cm in length. It varies in colour from bright violet to deep blue grey or orange. It is found well away from the reef in silty sand.
Carapace: The carapace varies in colour from purple to a rich orange-brown. It usually lacks ornamentation but in younger animals, there are longitudinal darker purple stripes that are continuous with similar stripes on the abdomen.
The abdomen is a uniform pink-brown or violet colour with darker stripes dorsally.
The rostrum and the antennae are deep purple. The pincers are flattened, uniformly coloured and may be very hairy.
The tail is purple-grey with purple outlines to the scutes.
The legs are usually dark purple.
Identifying feature
The purple colour of antennae, legs and usually carapace and abdomen is unusual and there is little problem in identifying this shrimp.
The strongly coloured purple antennae are very characteristic and are often the first indication that the burrow is occupied by Violet Shrimps.
Variation
Violet-coloured shrimps are the most common but there are also orange, pink and some brown individuals around. The latter colour form is more common on black sand and in larger individuals. As they coexist and mixed-colour individuals do occur we have considered these variants to be the same shrimp. Anker (2010) considers that there are more than one species. Ryanskiy (2016) has beautiful images of part violet and part brown individuals.
Similar Shrimps
None
Nomenclature
The scientific name Alpheus fenneri, Bruce, 1994 has been applied to this shrimp.
Anker (2010) considers that the name Alpheus fenneri possibly involves 2 species
Ryanskiy (2016) p7. has images of a similar-looking shrimp and gives the name Alpheus fenneri, common name Fenner’s Snapping Shrimp. Length up to 7 cm. Distribution Western Pacific – Japan, Philippines, Indonesia, Papua New Guinea, Australia. Commensal with Amblyeleotris fontanesii.
Hayashi & Shiratori (2003) Alpheus species 8 from Japan.
We have not seen this shrimp form a pair with any of the other shrimps described in this book.
Ecology
HABITAT
Preferred substrate Soft and very silty sand in sheltered bays.
Depth range 5 to 30 metres
Proximity to reef Well away from the reef.
NATURAL HISTORY
We have consistently found Alpheus fenneri in silty conditions near the islands of the Great Barrier Reef, sometimes with scattered seagrass Halophila, at 5 to 30 m depth.
Behaviour
The Violet shrimp grows to be big and strong. It makes a substantial burrow and is one of three robust shrimps that make most of the burrows in heavy silty conditions.
It is generally stated that this shrimp is only found with Amblyeleotris fontanesii. This is far from true and several shrimpgoby species form associations with this shrimp, notably some of the larger species such as Cryptocentrus cebuanus Cebu Shrimpgoby and Tomiyamichthys smithi Smith’s Shrimpgoby. Other associations are more common with small violet shrimp. What they all have in common is that they live in silty conditions well away from the reef.
Distribution
Published Distribution:
Western Pacific: Japan, Philippines, Indonesia, Papua New Guinea, Australia, Ryanskiy (2016). Flores, Indonesia, Kuiter and Debelius (2009).
Our records:
Australia; Fitzroy Island, Low Isles, Percy Islands.
Papua New Guinea; Normanby Island.
Solomon Islands; Ghizo, Guadalcanal, Kolombangara.
Associated Goby species
Associated Shrimpgobies (nine species)
Usual associations
Amblyeleotris fontanesii, Giant Shrimpgoby
Other associations
Cryptocentrus cebuanus, Cebu Shrimpgoby
Cryptocentrus sericus, Ventral-barred Shrimpgoby
Tomiyamichthys nudus, Scaleless Shrimpgoby
Tomiyamichthys smithi, Smith’s Shrimpgoby
Tomiyamichthys tanyspilus Longspot Shrimpgoby
Vanderhorstia auronotata, Gold-Marked Shrimpgoby
Vanderhorstia papilio, Butterfly Shrimpgoby
Other Records
Amblyeleotris macronema, Longspine Shrimpgoby (visual record) No photo available