![]() Through the co-ordinated beating of myriad whip-like flagella, they draw in water through the pores on their external surfaces, circulate it through a labyrinth of body cavities, then pump it out, usually through large openings called oscula, which are often raised above the surface on turrets that look like the cooling towers of power plants.Ĭonsidering the simplicity of their activities, the diversity of their architecture is dazzling. ![]() Porifera, the name of their phylum, means ‘pore-bearer’, and they bear millions. They may appear immobile, but these sponges can move up to a few millimetres per day, and have surprisingly complex rhythms, often shutting down their pumping activity for days at a time. Their reticulate skeleton, made up of spicule-stiffened fibres, can be seen with the naked eye. Solid, spherical and brightly coloured, like knobbly golf balls, sponges of the genus Tethya are a common sight in rock pools and shallow waters around New Zealand. They spend their days and years (and some live for thousands of years) filtering small particles from seawater. They don’t travel much, either, though some individuals have been observed to move a few millimetres in a day. (Even the great Linnaeus mistakenly thought sponges were algae.) They lack nervous, digestive and circulatory systems. I use the word ‘critters’ advisedly because, despite appearances, they are animals. These are the critters to which I devoted two years of my life. They come in every colour of the paint chart, and range from delicate lacy creations to massive structures metres thick and the consistency of hard-packed snow. They inhabit the wave-splashed shallows of rock pools and the dark stillness of abyssal depths. They are present in every ocean, from pole to pole, and some have conquered fresh water. ![]() Classifying them is a gargantuan task because sponges are a vast tribe there are perhaps 10,000 species. The following year, I enrolled for a master of science degree in marine zoology, with Bergquist as my supervisor. She made them exciting-surprising as this may sound-and I was captivated. Bergquist (Dame Patricia, as she became in 1994, when she was made a dame commander of the Order of the British Empire) was a world authority on the spineless creatures. I was in Pat Bergquist’s invertebrate zoology class, at the University of Auckland, in 1975. I can’t fully recall how the affair started, it was so long ago. Written by Kennedy Warne Photographed by Richard Robinson
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