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Role of starfish in the ecosystem

In this video Dr Miles Lamare, from the University of Otago, discusses the classification of starfish and the role that they play in the marine ecosystem.

Point of interest
Starfish is the common name for a group of animals called sea stars. Sea stars are actually part of the phylum echinoderm and are related to sea urchins, brittle stars and sea cucumbers – they are not fish at all!


A starfish is a marine invertebrate. Invertebrates make up around about 95% of the animals in the ocean, so they are the most common major group. Starfish belong to a phylum or a big group of animals called echinoderms, and that includes starfish, sea urchins, brittle stars, sea cucumbers and something called a feather star. So starfish are predators, and they’re probably the most important predator in the shallow ecosystem – so the depths where we would dive or swim. They eat basically anything that they can come across. Their feeding activities control the whole ecosystem. It comes back to the concept of a keystone species – if that species is affected, it’s going to have a disproportionately greater effect on the whole ecosystem because you’re removing a key component. So we are trying to really quantify what their feeding is doing in the local environment, particularly in places like Fiordland. So we are really trying to understand quantitatively, exactly how they feed, how often they feed, where they are feeding, and what they are feeding on, to try and understand their role as a keystone species, which would lead on to answering questions such as what would happen if the starfish numbers were reduced or something was interfering with their normal behaviour.

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