Water Slater

Asellus aquaticus

Statistics

Taxonomic family: Asellidae

Length: 0.5 to 2 cm

Average life span: less than 2 years

When To See

Commonly found in the river all year round.

Photo credit: The Free Social Encyclopaedia, Iain Reid

Habitat

Water slaters or hoglouse are aquatic crustaceans found frequently in rivers and ponds.  They are tolerant to pollution so if you find large numbers of these and few other species then it is a sign that a pollution incident may have occurred. Hoglouse breed throughout the year, sometimes producing two generations in a single year. Like most cold blooded creatures their growth rate and metabolism is dependent on the temperature of the water; the warmer the water, the faster they grow.  This also means that they are more active in the summer when the water is warmer.

How To Identify

They are related to (and look similar to) a garden woodlouse but live entirely in water. They have two distinctive pale spots on the head. The less common One-spotted Water Slater looks the same but with one pale spot.

Seen It?

Been kicking about in your local river and come across one of these invertebrates? Not sure? Share it with us at trust@forthriverstrust.org, we enjoy chatting about inverts with you.