Ancylomenes holthuisi
Translucent, near-invisible on its host anemone. Find it in Visayas, Sai Kung and Nusa Tenggara, in warm 23-30°C reef water year-round.
A small, glassy-bodied shrimp that reads as almost see-through against the anemone it perches on, often with faint white or purple speckling along the body and thin banded legs. It sits low and still on the tentacle crown rather than swimming freely, which is usually the first clue to spotting one. Size is easy to overlook underwater, so most divers find it by scanning host anemones closely rather than by colour alone.
Found parked on the tentacles of its host anemone, usually holding station rather than roaming the reef, which makes it a slow, patient find rather than a chance encounter while swimming past. It tends to shuffle deeper into the tentacles when a torch or camera gets close, so a still, low approach works better than a direct hover. Most logs come from daytime reef and rubble dives where divers are already searching anemones for other small residents.
Like many anemone shrimps, it lives in a mutual arrangement with its host, gaining protection from the stinging tentacles while it picks at debris and parasites, a relationship that makes it worth checking every anemone on a dive rather than just the obvious ones.
Sightings show no clear seasonal pattern, and the shrimp's comfort range of roughly 23 to 30°C spans typical tropical reef conditions year-round, so any month is fair game.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
Most reliably logged in the Philippines, especially across the Visayas, with strong site counts also in Hong Kong's Sai Kung region and Indonesia, particularly Nusa Tenggara and Sulawesi. Across all three countries it turns up as an uncommon but steady find on anemone-covered reef and rubble sites rather than being restricted to one signature location.
Mapping where Holthuis' Anemone Shrimp is logged…
It is most commonly logged across the Visayas in the Philippines, Sai Kung in Hong Kong, and Nusa Tenggara and Sulawesi in Indonesia. At most of these sites it counts as an uncommon sighting rather than a guaranteed one.
There is no strong seasonal pattern in the sightings, and it tolerates the 23 to 30°C range typical of tropical reefs year-round, so it can turn up on any month's dive.
Look for a small, near-transparent shrimp sitting motionless on an anemone's tentacles, with faint speckled markings and banded legs. It blends in well, so a slow scan of the whole anemone works better than looking for bold colour.
Exact size figures are not well documented for this species, but like most anemone shrimps it stays small enough to be easily missed against its host without a close look or a macro lens.
No, it poses no risk to divers. It is a small, harmless anemone-dwelling shrimp best appreciated at a respectful distance so as not to disturb its host.
It lives in a cleaning partnership with its host anemone, sheltering among the stinging tentacles while picking off parasites and debris, a trade-off shared by several anemone shrimp species divers look for on the same dive.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Freshwater Shrimp
2,168 sites
