Palaemon macrodactylus
Translucent, uncommon shrimp logged across Zeeland's cold Dutch waters at 9-15C, year-round if you know where to look.
A small, slender shrimp reaching about 5 cm, with a translucent to pale grey-brown body that lets it blend into silt and low-light water. Look for a long, saw-edged rostrum (the pointed spike between the eyes) and faint darker speckling along the back rather than any bold pattern. There's no dramatic colour difference reported between individuals, so size and that thin, near-see-through body are the main giveaways.
Divers mostly find it sitting or picking its way slowly over silty or weedy bottoms, low down where visibility and light are often reduced. It's not a shy animal exactly, but its plain colouring and small size mean it's easy to swim straight past unless you're already looking close to the substrate. Most logs describe it as uncommon rather than clustered in groups, so a careful, slow pass over the bottom is more productive than searching open water.
This species is native to East Asian estuaries and has become an established non-native population in parts of Europe, including Dutch coastal waters, which is likely why it turns up so consistently in Zeeland logs despite the region sitting outside its original range.
Sightings show no clear seasonal pattern, and with a water-temperature niche of roughly 8.8 to 14.8C, it's turning up across the colder end of the diving calendar rather than only in a warm-water window. Treat it as a year-round possibility on Zeeland dives rather than a species tied to one month.
Every logged sighting in this dataset comes from the Netherlands, with Zeeland standing out as the region where divers reliably find it. If you're diving Dutch inland or coastal sites in Zeeland, this is one of the small crustaceans worth scanning the bottom for.
Mapping where Oriental Shrimp is logged…
Nearly all logged sightings come from the Netherlands, with Zeeland the standout region for finding it. It's worth checking silty or weedy bottoms on Dutch dives rather than expecting it on tropical reefs.
There's no strong seasonal pattern in the sightings, and it's recorded across a fairly cold water-temperature range of about 9 to 15C, so it's a realistic year-round find on Zeeland dives.
Look for a small, translucent to pale brown shrimp around 5 cm long with a thin, saw-edged rostrum between the eyes and no bold colour pattern. It tends to blend into silty bottoms, so slow, close searching helps.
They reach around 5 cm in length, making them a small, easy-to-miss find rather than a showy reef animal.
No, they pose no danger to divers. They're a small, harmless crustacean best appreciated with a careful look rather than handling.
It's originally native to East Asian estuaries but has established non-native populations in parts of Europe, including Dutch coastal waters, which explains its consistent presence in Zeeland dive logs far from its original range.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Freshwater Shrimp
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