Land Hopper - Arcitalitrus sylvaticus.
Image: David Staples
Source: Museum Victoria
Question: I don’t live near the beach but keep finding prawns in my house – why?
Answer: These invertebrates are not prawns but a species of amphipod, commonly called land hoppers or lawn shrimps. There are thousands of species of amphipods, the majority of which live in the marine environment. However a number of species are terrestrial and they all require a moist environment in which to survive.
Amphipods are laterally compressed meaning they are taller than they are wide. It may be for some of the marine species that this aids in moving through dense plants. If you have ever lifted a pot plant or raked through leaf litter in a forest or even your garden you may have noticed these land hoppers jumping around. They can achieve this by a sudden flexing of their abdomen and the random and rapid way in which they jump around makes it hard for predators to catch them.
Amphipods are an important food source for many animals in the sea and on land; amphipods themselves generally feed on decaying plant material but there have been some cases of cannibalism.
Sometimes following heavy rain amphipods can be flushed from their usual home in leaf litter and end up coming into peoples homes or garages or falling into their swimming pools. Usually on coming inside they rapidly dry out and die and many become a red or pink color, again contributing to people thinking of them as prawns or shrimps. These invertebrates should not cause any damage to the contents of a house and present more of a nuisance value than anything else. If they come inside and die, simply sweep them up and throw them out.
Try not to have moist, deep leaf litter near doors as this may encourage populations of amphipods and if you get repeat incursions of amphipods into your home try making the cracks under the door smaller by using draught excluders.
Melbourne’s Wildlife: a field guide to the fauna of Greater Melbourne.
Published by Museum Victoria and CSIRO Publishing, 2006.