The wharf roach is a fast, roach-like crustacean that swarms over seawalls, jetties, and rocks just above the waterline. In the United States it is an introduced species, found along the East Coast and in Hawaii. It is also called the sea roach.
Appearance
- Appearance
- Up to about 1.6 in (4 cm) long, with males larger than females. The flat, oval body is dark gray, sometimes flecked with brown, with antennae longer than the body and a pair of long forked tail appendages.
Look-alikes
Ligia baudiniana
The two are hard to tell apart in photos, and even experts have mixed them up. Location helps: Ligia baudiniana is a Caribbean native that reaches only the southern tip of Florida, so a sea roach elsewhere on the Atlantic coast is most likely the wharf roach.
Why they get mixed upBoth are fast, flat sea roaches on rocks and seawalls, and they can occur together in South Florida.
Where it lives
- Typical habitats
- Jetties and seawalls
- Rocky shores
- Harbors
- Range
- Probably native to East and Southeast Asia. In the U.S. it lives on the Atlantic coast from New Jersey south to Florida, with older records along the Gulf of Mexico, and in Hawaii (first reported in 1996). It appears to be absent from the Pacific coast of the mainland U.S.
- Preferred conditions
- Lives in damp cracks in the splash zone just above high tide. It cannot survive long underwater and does not venture into open water.
Behavior
- Diet
- Grazes on microscopic algae and diatoms and scavenges plant debris and other scraps.
- Activity
- Often seen in large numbers on harbor walls, where it dashes for cover when approached.
Life cycle
- Reproduction
- Females produce batches of about 80 eggs and carry them under the body. Young hatch looking like small adults and molt several times as they grow.
- Larva
- There is no free-swimming larval stage, so it cannot spread far on its own.
Name and classification
- About the name
- Genetic studies show that what has been called Ligia exotica includes several deeply separated lineages that may be different species. Only a couple of them have spread around the world, likely carried in wooden ships and ballast during the 1700s and 1800s.
Conservation
- IUCN Red List
- NENot EvaluatedNot yet assessed
- Threats
- On the East Coast it is considered invasive and appears to be the dominant invertebrate in its habitat, though its effects on native species have not been well studied.
More species to explore
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