| Mollusks consist of four main groups: Cephalopoda, Polyplacophora, Gastropoda, and Bivalvia. Polyplacophora include organisms with exterior shells, such as chitons. Gastropoda include nudibranchs which are slugs, and most have a distinct feature of a flower on their back, which are gills. Bivalvia are mollusks completely covered with a shell. Cephalopoda are not found in the intertidal, because they live in the open ocean. In the five sites we visited, we found a total of 33 species. Most of our sites had Dendropoda gregaria and Dendropoda platypus which are bivalves (aren’t they Dendropoma vermetids?) and were always found together. All of the mollusks we found were either endemic or native. It is easier to find chitons and slugs in rocky areas with less wave action, such as Ewa Beach. The radula is used to scrape off food on rocks and corals. Under the radula is a subradula, which chemically checks food particles. Some mollusks are carnivorous, but ome areC herbivorous. Most of the slugs like eating sponges, bryozoans, or hydroids, and keep the populations under control. We found most slugs and chitons at Kahana Bay because there were tons of rocks and weaker waves like we said earlier. At other sites that we visited with our helper Ms. Anuschka, we were able to find and identify many types of vermetids, which are tube species on rocks. We found them at Coconut Island that had tons of rocks. So it is good to have an expert to help you find mollusks. When out in the field, mollusks pose little danger. The only thing is that some are sharp shells and can give you a cut, so bring a first aid kid. Oh yeah, stay away from bright-colored like orange because they are toxic.
A slug is a small invertebrate with no exoskeleton. Since they have no exoskeleton, they have toxins in their skin to protect themselves from predators. Nudibranch means naked gill. Its gill is on its back. Nudibranchs are colorful, ranging in many different colors, while sea hares are usually darker in color and don’t have a naked gill on their back. Sea slugs don’t have many predators, because they don’t taste good because of the toxins in their skin. They have many prey though. Certain species eat certain organisms. They feed mostly on algae and other nudibranchs. They use a radula, a rasp-like tongue, to eat. Sea slugs are hermaphrodites, which means they have both male and female organs. When they mate, they poke each other with reproductive organs. Whoever gets poked first acts as the female and carries the eggs. They lay thousands of eggs usually in a spiral. This project gave us a hands-on experience with slugs. We went to five different sites, Diamond Head, Coconut Island, Kahana Bay, Sandy Beach, and Ewa Beach, searching for slugs and other mollusks. Our main focus was slugs because they were most common. We collected over 30 species. We were able to identify all of the ones we found. Isognomon californicum and Isognomon perna were the most common mollusks we found. We found those at most of the sites we visit. This project was done over several months, which helped us learn about several different mollusks, including slugs, bivalves, chitons, vermetids, and limpets.
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