Head to head
Water Louse vs Woodlouse
Water Louse
VS Woodlouse
The water louse and the woodlouse are close cousins, both isopod crustaceans with flat, armoured bodies, but one lives under water and the other on land.
| Water Louse | Woodlouse | |
|---|---|---|
| Scientific name | Asellus aquaticus | Oniscidea (the woodlouse group) |
| Relationship | An aquatic isopod, a cousin of the woodlouse | A land-living isopod, a cousin of the water louse |
| Habitat | Ponds, lakes, canals, and slow rivers across Europe and northern Asia | Every continent except Antarctica, in damp sheltered spots such as under logs and stones |
| Body | A flat, oval, grey-brown body of overlapping plates, usually 1 to 2 cm long | An armoured body of overlapping plates, grey to brown |
| Breathing | Takes oxygen from the water | Breathes through gill-like structures on its underside, and in some species through folded air-filled lungs |
| Diet | Rotting leaves, algae, and dead plant and animal matter | Mostly dead and decaying plant material such as leaf litter, rotting wood, and fungi |
| Special feature | The male holds on to the female and carries her for several days before they mate | Pill bugs can roll into a tight ball, and a woodlouse sheds its shell in two halves a few days apart |
| Conservation status | Not Evaluated, but abundant and tolerant of poor water | Not Evaluated, and found in almost every land habitat with some moisture |
Water Louse vs Woodlouse: common questions
Is a woodlouse an insect?
No, woodlice are crustaceans, in the same broad group as crabs and lobsters, and the water louse is their aquatic cousin.
Which one can roll into a ball?
Some woodlice, called pill bugs, can roll into a tight ball, but the water louse cannot.
Which one lives in water?
The water louse, which lives in ponds, lakes, canals, and slow rivers, whereas the woodlouse lives on land.