Sea lice (plural) are marine crustaceans that live in shallow waters worldwide. They live buried under the surface of the sand, and at night actively swim in search of food. Sea lice are scavengers that feed on dead or dying fish and other animals. Some sea lice species are very common and are often found in large numbers.
Sea lice can be significant pests for commercial fishers, devouring fresh bait and captured fish from traps and lines. Their abundance and ability to rapidly devour food items means sea lice, and some other crustacean scavengers, can be damaging to fishing operations. Sea lice are also renowned for the sharp bites they sometimes inflict upon swimmers. 'N woodjonesi' populations can take just hours to reduce a fish carcass to a skeleton.
'N woodjonesi' grows to 25 mm long and has a shiny white body with black eyes on the side of the head. The last legs are fringed with hair and the spiky tail segment has a pair of pointed tail limbs that form a tail fan.
Sea lice belong to a crustacean group called isopods. Isopods are characterised by having abdominal gills, just one pair of tail limbs, and no clawed pincers. Isopods are highly diverse in body form - they may be flattened or thin, and they range in size from microscopic to a 40-cm-long deep-sea species.
There are marine, freshwater and terrestrial isopod species, and all forms of feeding habits are seen in this group. Some isopods are scavengers feeding on dead fish, others are parasites or predators, and some are herbivores that feed on seaweed. Isopods mostly creep along like insects, but many aquatic species can swim.
This 'N woodjonesi' specimen was among thousands of marine animals collected from Port Phillip Bay, Victoria, as part of the Port Phillip Bay Environmental Surveys of 1969-73 and 1992-96. These surveys, conducted by government departments and Museum Victoria, were concerned with the environmental condition of the Bay and changes in benthic communities (those found on or in sea floor sediments). Invaluable information relating to the density and distribution of native and introduced species were obtained, and thousands of previously unknown species were identified.