Catching a Ride with Bull Kelp

Diloma snails feeding on bull kelp. Image courtesy of Alison Ballance

Bull kelp (Durvillaea antarctica) is the very large tough brown seaweed that thrives on rocky surf beaches in the south of New Zealand. It has leaves that can be up to 10 metres long, and the plant is attached to the rock by a strong base, or holdfast, that 'glues' the plant onto the shore. The leaves of bull kelp are honeycombed and filled with air spaces, so if a plant breaks off in the waves it can float. Lots of small creatures such as crustacea and snails live within the holdfast, so if the kelp plant floats away, it takes all these creatures, becoming their floating 'hotel and restaurant'.

A team of biologists from the University of Otago (Crid Fraser, left, Jon Waters and Raisa Nikula, left, pictured with a bull kelp holdfast that had washed up on a beach) has been looking at how bull kelp is distributed around the Southern Hemisphere, the genetics of the plant, and the creatures that live within it, and they have come up with some unexpected results. Find out more about their research.