Marine life without a backbone

There are two marine invertebrate specialists from the Australian Museum along on the expedition, and when you think that invertebrates are all animals without a backbone, you’ll appreciate they are looking for an enormous variety of creatures. They could be looking for really tiny animals the size of a full-stop that live in between grains of sand, or something as huge as a giant squid – and every size in between.

Mandy Reid is an expert in molluscs – snails, octopus and sea slugs, for example – and her speciality is squid. Stephen Keable is an expert in crustaceans – think crabs and shrimps – and he is most interested in marine isopods (common garden slaters are a familiar isopod). But they are not just looking for the animals that interest them the most – they are also taking back lots of things for other people to look at.

Mandy and Stephen collect samples in many different ways. When they dive they are often collecting what they call ‘substrate’, which are the places where little critters live (since the animals themselves are too tiny to see it’s easier to collect their homes!). So, they might gather up a handful of rubble from the sea floor, gather clumps of algae or a coral branch. They are also on the look-out for interesting larger creatures. Back on board they wash the algae in seawater, gathering up anything they can see with the naked eye, and straining the water through a fine sieve to catch all the tiny animals that they will later identify under a microscope.

On their first dive they brought back this large crown-of-thorns starfish. This starfish is notorious for sometimes causing lots of damage on tropical coral reefs, but although we’ve seen a few around the Kermadecs, they seem to be happily living alongside everything else and not causing trouble.

Crown of thorns starfish: notorious for causing damage on tropical coral reefs but in the Kermadecs they seem to be happily living alongside everything else

Crown of thorns starfish: notorious for causing damage on tropical coral reefs but in the Kermadecs they seem to be happily living alongside everything else

Many of the invertebrates are brightly coloured – look at this luscious orange sea star!

Star bright: a luscious orange sea star

Star bright: a luscious orange sea star

Phytoplankton are tiny plants that float in the water – they occur in huge numbers and are the powerhouse of the whole marine food chain. If phytoplankton are like the grass of the sea, then the zooplankton that graze on them are like marine sheep! They are tiny crustaceans, and in their turn they feed all the bigger animals. At night, Stephen scoops a small hand net through the water to collect zooplankton that swarm at the surface, attracted by the boat lights. Steve then washes the contents of the net through a little sieve, and puts everything in a jar to take back to the museum for someone to sort through later under a microscope.

Invertebrate expert Stephen sieves water for plankton

Invertebrate expert Steve sieves water for plankton

Look how many kinds of plankton Steve collected from one scoop – and while some of the plankton are just like clear jelly, others glow like little jewels.

Single scoop please: multiple types of plankton in just one ocean scoop

Single scoop please: multiple types of plankton in just one ocean scoop

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4 Responses to “Marine life without a backbone”

  1. Angela Low

    Hi Steve,

    That looks much more fun than sitting on a computer! I was wondering where my kitchen strainer had got to?!?

    Look forward to the stories (and specimens) when you return.

    cheers Angela

    Reply

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