Shellfish
Yaeyama mangrove clam / Geloina erosa / Yaeyama hirugi-shijimi / ヤエヤマヒルギシジミ
This species of clam is found on Amami-Oshima in river mouths and mangroves, where it feeds on nutrients in the mud and the estuary waters. It is large, usually fist-sized, and the shell has a dark-brown exterior with a white interior. This bivalve can survive the harsh conditions of the tidal mangrove environment by staying closed while the tide goes out, holding water inside until the next high tide. It plays an important role in mangrove ecology by filtering polluted waters as it feeds.
Common oriental lamp shell / Lingula anatine / Midori shamisen-gai / ミドリシャミセンガイ
This marine animal is a member of the brachiopod family, with valves on both surfaces of its hinged shell. It is often mistaken for a member of the clam family. It is about 3 centimeters long, flat, and almost rectangular with one pointed end. The brownish-green shell has a long stalk, called a pedicle, that extends from the back end; this is used to burrow in sand or mud. The lamp shell is a filter feeder that extracts food from brackish intertidal waters. The similarity between the lamp shell and ancient fossils led Darwin to coin the term “living fossils” to describe organisms that have not evolved (though this is now widely considered to be scientifically incorrect). This brachiopod’s Japanese name, midori shamisen-gai, or “green shamisen clam,” refers to its resemblance to the traditional long-necked stringed instrument.