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Landhoppers
Phylum Arthropoda
47.3492, -122.556
Field Notes
Description:
Amphipoda is another group of Crustacea (see Isopoda) that has adapted to living on land. Most amphipods are aquatic, with the majority being marine. Other amphipods live in the tidal zone and on beaches, and can be considered semi-terrestrial. One group – the landhoppers – have become fully terrestrial. All terrestrial amphipod species belong to the family Talitridae. There are marine and semi-terrestrial Talitridae as well.
Landhoppers are usually 0.5-1.5 cm in length, and somewhat shrimp-like in appearance. Their bodies are elongated and compressed laterally, and have a smooth and shiny appearance. The males can be smaller than the females. Live land hoppers range in colour from pale ochre or grey to olive- or reddish-brown, often with a pattern of stripes and spots. In a manner similar to shrimp and lobsters, landhoppers turn red once they are dead.
Terrestrial amphipods have elongated body with a distinct head, 7 thoracic segments, and 6 smaller abdominal segments. The head bears two pairs of antennae (one pair long and conspicuous, and the second pair very small), two large compound eyes, and chewing mouthparts. On each thoracic segment there is a pair of appendages. The first two pairs - gnathopods - are modified for food processing; the appendages on segments 3-7 are legs. The last two pairs of legs are particularly long, robust, and used for jumping. The gills, if present, are located at the bases of the thoracic legs. The abdominal segments bear leg-like appendages: pleopods on 2nd and 3rd abdominal segments, and long, backward-facing uropods on segments 4 and 5.
Habitat:
Terrestrial amphipods are restricted to sheltered, damp environments. They inhabit the leaf litter and soil of native forests, tall grasslands, scrublands, parks and gardens. In Fiordland, landhoppers were found living in the moss of tree canopies. Several native species dig burrows in the soil, or use burrows made by other soil invertebrates. Often landhoppers can be found around human houses in garden mulch, compost, under dense ground cover plantings, or under any damp pile of plant debris. Many related semi-terrestrial species (sandhoppers) can be found on the beach, where they live under driftwood, stones, and piles of decaying algae.
When uncovered in their shelters, landhoppers rush to escape the light, and will disappear within seconds. They are quite difficult to capture or to photograph. Unlike slaters (Isopoda), terrestrial amphipods are difficult to keep in captivity. They are very sensitive to their environment, and die quickly if the conditions are too dry or too moist.
Landhoppers can be collected directly, or in pitfall traps. Berlese funnel extractions often yield amphipods, although care should be taken that large active specimens do not escape from the sample during collecting. Landhoppers can be preserved in 70% alcohol, which needs to be changed periodically.
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