Sicyonia carinata
Uncommon but findable in Murcia, Spain and the French Riviera, this small armoured shrimp turns up year-round in 15-21C water.
A stocky, armour-plated shrimp around 6 cm long with a hard, ridged carapace rather than the smooth translucent body of most reef shrimp. Colour runs reddish-brown to sandy tan, which helps it blend against rubble and sediment. The body looks boxier and more heavily armoured than typical swimming shrimp, with a short, thick tail fan instead of a slender one.
Divers typically find it sitting still on sand, rubble or mixed seabed rather than swimming in the open water column, relying on its armoured shell and camouflage to avoid attention. It tends to hold its position when approached slowly rather than darting away, which makes it an easy subject once spotted. Most logs come from uncommon sightings rather than dense clusters, so expect to search rather than stumble on numbers.
That thick, ridged carapace is a real defence strategy: unlike thin-shelled reef shrimp, rock shrimp rely on armour rather than speed to deter predators, which is why they sit tight instead of fleeing when divers approach.
No clear seasonal pattern shows up in the sighting data, so treat it as a year-round find within its 15 to 21C comfort range. Divers log it across the seasons at the same sites rather than in a single peak month.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
Most reliably logged in Murcia in southern Spain, which accounts for the bulk of recorded sightings, with additional records from France's French Riviera, Provence, and Occitanie coasts. Spain is by far the stronger country for this species, with France a secondary but real option.
Mapping where Mediterranean Rock Shrimp is logged…
Murcia in Spain is the strongest area for sightings, with further records along France's French Riviera, Provence, and Occitanie coasts. Spain accounts for most logged sites overall.
There's no detected seasonal peak, so they're considered a year-round sighting in waters between 15 and 21C. You have roughly even odds across the seasons at known sites.
Look for a small, thickset shrimp around 6 cm with a hard, ridged shell in reddish-brown to sandy tones, sitting still on sand or rubble. The boxy, armoured body and short tail fan set it apart from smoother, more streamlined reef shrimp.
They reach around 6 cm in length, making them a small, easy-to-overlook find on the seabed.
No, they pose no danger to divers. They are small, sedentary, and rely on their armoured shell rather than any defensive behaviour toward divers.
Instead of the thin, near-transparent shell most reef shrimp have, this species carries a thick, ridged carapace as its main defence, letting it sit exposed on open sand rather than hiding in crevices.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
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