Nematode
A nematode is a roundworm. One kind of this worm found in the American Samoa is the palolo worm. They are found in tropical waters and there are over 14 species of palolo worms. Their larvae disperse widely, which is why the worms are found in most tropical and temperate oceans of the world. Their role in the ecosystem is to contribute to the richness of American Samoa marine diversity and at the same time an important factor for their cultural cohesion.
Annelida
Annelids are segmented worms. Leeches (found in many habitats such as American Samoa), do not have bristles and the external segmentation of their bodies does not correspond with the internal segmentation of their organs like most annelids. Their role in the ecosystem is to keep balance and so that all living creature species stay alive. Leeches are sometimes important members of aquatic food webs.
Mollusca
Molluscs are invertebrates. They are highly diverse, not only in size and in anatomical structure, but also in behavior and in habitat. Nautilus (found in surrounding waters of American Samoa), are marine mollusk with a coiled chambered shell; nautilus are known to be called "living fossils", because it's ancestors date back to over 500 million years ago. Their role in the ecosystem is animal waste, essentially keeping water clean and healthy. They control the numbers of species such as hermit crabs and fish by preying on them.
Proifera
Porifera are multicellular organisms whose bodies are full of pores and channels allowing water to circulate through them.Yellow Sponge (found in coral reefs around American Samoa), spread over coral and rock formations in the reef environment; despite its name, the yellow sponge is usually bright orange in color. Their role in the ecosystem is to breed and nurse areas for fish and invertebrates.
Cnidaria
Cnidaria is a group of aquatic invertebrates. Thimble Jellyfish (found in surrounding waters), show radial symmetry and have eight gonads arranged in pairs. Their role in the ecosystem is to control populations of planktonic organisms like crustaceans and fish larvae. Some species of sea turtles and seabirds feed on jellyfish.
Echinodermata
Echinoderms are a taxonomic group which consists of marine invertebrates of radial symmetry. They have no head and have a water-vascular system. Crown-of-thorns starfish (found on coral reefs at the bottom of the ocean), are almost completely covered in venomous spines that can be incredibly painful to humans if touched. Their role in the ecosystem is to control many species in the entire ecosystem.
Crustacae
Crustacea have have a hard, external shell which protects their body. Crustaceans have a head and abdomen. The head has antennae which are part of their sensory system. Samoan Coconut Crab (found in the ocean and on land), is the largest land living arthropod in the world. Their role in the ecosystem is to manage the populations of the animals they prey on. They are scavengers and provide a food source for their predators.
Arachnida
Arachnids are joint-legged invertebrate animals in the subphylum Chelicerata. Samoan Moss Spider (found in the forests of American Samoa), are the smallest spider in the world measuring a mere 0.1 inch long in length and a leg span of 0.0179 inches. Thier role in the ecosystem is to control the numbers of the species of their prey. Other than that there is no other role in the ecosystem.
Insecta
Insects are invertebrates that have an exoskeleton made of the protein chitin, a three-part body, three pairs of jointed legs, compound eyes and one pair of antennae. Samoan Swallowtail Butterfly (found all over the islands of American Samoa), have recently died out in Samoa but still thrive in the neighboring American Samoa. Their role in the ecosystem is to pollinate plants and flowers.