Urchin Photos

underwater photos of sea urchins, starfish and sea cucumbers

By Floor Anthoni
www.seafriends.org.nz/images/urchin.htm
(A5@300dpi)

The echinoderms (prickly skins) comprise the sea urchins, starfish and sea cucumbers. They have evolved into a great variety of shapes and living styles.

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Keywords: NZ, New Zealand, sea urchin, urchin, sea egg, kina, Evechinus chloroticus, purple urchin, Centrostephanus rodgersi, diadema, Diadema palmeri, short spined, Tripneustes, sea star, starfish, cushion star, Stegnaster inflatus, Astrostole scabra,

common green urchin Evechinus chloroticus

f007212: the barren zone is started by a large storm, removing kelp from areas that are too exposed for them. Sea urchins then move in to maintain the barren patch, and to enlarge it. Evechinus chloroticus

f013229: urchins attacking stalked kelp. Once the kelp starts bleeding, other urchins are attracted by smell. Evechinus chloroticus

f001319: urchins (Evechinus chloroticus) have cleared an area, and other grazers move in. In the background the sturdy and powerful grazers, the Cooks turband shell (Cookia sulcata), grazing into the bushy form of the stone-leaf alga, also called pink paint (Lithothamnion). The smooth bits are grazed by top shells, catseye (Turbo smaragdus) and radiate limpets (Cellana radians), all just visible under their coats of pink paint.

f001932: where the rocks slope gently inside the urchin's habitat zone, one may find large barren areas like the one shown here. Some urchins have clustered on the sheltered side of the rock, but a leatherjacket visits them for a nip at their tubefeet and spines. Although the rocks look barren, they are nevertheless highly productive, as borne out by the numerous other grazers found here.

common green urchin Evechinus chloroticus and stalked kelp

f006828: the last Mohican? Evechinus chloroticus

f019724: an urchin has climbed halfway up a stalked kelp where it will bite through the stipe, bringing its crown down. The urchin's five-pronged teeth are only just visible.

f020710: a juvenile needle urchin has five white sectors. Here it is seen browsing over a tapestry of carpet sponges. These urchins do not graze , but they catch live prey inside their very agile spines.

f020712: closeup of the juvenile needle urchin shown left (Diadema palmeri).

f031117: although still spectacular, the mature needle urchin has less variety in colour.

f020136:

f020137:

f030417: the blue needle urchin is rarely seen.

f020134: the purple urchin (also called black urchin) (Centrostephanus rodgersii) has thick, sturdy spines. It prefers the clearer waters of the offshore islands of New Zealand, and occurs a little deeper than the common urchin.

purple urchin Centrostephanus rodgersii and demoiselles

f021819: because of its larger spines, the purple urchin can give good protection to juvenile fish, like these young two-spot demoiselles (Chromis dispilus). Centrostephanus rodgersii

f030424: in this closeup of the purple urchin the purple colour and greenish sheen can clearly be seen. Centrostephanus rodgersii

f029818: this white-spined urchin is occasionally found around our offshore islands (Tripneustes sp?). It stands out by the sheer density of its red tube feet.

f029825: the white-spined urchin is found from 3-25m, covering a wide range and an equally wide range of diets. Rather than grazing on barren rock, it prefers the lush growth of fleshy seaweeds like sea lettuce and stalked kelp. Here it is seen hoarding its next meal on its back. Deeper down it climbs the kelp to feed on its fronds.

f004901: the ambush star or elevated cushion star (Stegnaster inflatus) has a peculiar but effective way of catching prey. By standing tippy-toed on its five arms, it forms an apparently safe shelter underneath. The catseye snaill in the foreground might be tempted to walk in. But as soon as the star's belly is tickled, it closes its web like the curtains of a stage, trapping the animal inside. Rasplike protrusions on its belly, move the victim further towards the stomach in the middle, as it fights to escape. This animal catches snails, crabs, shrimps, seahorses and small fish.

f014730: a collection of ambush stars, brought together to show their range of gaudy colours. For good measure, two common cushion stars (Patiriella regularis) are part of the scene. [A6]

f004904: When removed from its site, an ambush star curls its cardboard-thin web, which makes it more difficult to be eaten. ambush star Stegnaster inflatus

f001618: a large seven-armed prickly star (Astrostole scabra) has wedged itself in a crevice, while hiding its prey from prying eyes. Astrostole is perhaps the largest star known in New Zealand waters. It can grow to a diameter of 60cm. Its tubefeet are very strong, and when it is attached to a diver's wetsuit, is almost impossible to remove. Astrostole scabra

f001615: by gently bending one arm back, the hapless sea urchin can be seen underneath. But collectively, sea urchins are capable of fending off this strong predator. Among the urchin's tubefeet covering its back, are defensive tubefeet with three-pronged beaks. They appear to hurt the very much larger predatory star. Astrostole scabra

f013820: a Japanese student holds up a seven-armed star to show its size and what it is eating, a fully grown Cooks turban snail. Astrostole scabra

f013822: closeup of the seven-armed star and its meal. Astrostole scabra

f010702: a seven-armed star has suffered size reduction by the predating trumpet whelk (Charonia) who specialises on sea stars. After giving a star chase with large steps, the trumpet whelk pins it down with its large siphon, then steps onto the immobilised arm. Realising it has been trapped, the starfish then sacrifices its arm, running away with the others. But the trumpet whelk is persisten in its hunt, as this star has found out, but some of its arms are regrowing already. Astrostole scabra

f017234: a trumpet whelk (Charonia lampas capax) has just pinned down an eleven-armed prickly star with its siphon (Coscinasterias calamari), and is now going to place its large foot onto the caught arm. The victim has already lost one arm, which has started to regrow. This story had a happy ending because the uneven topology of the oyster bed, allowed the star to escape. The star shape enabled the victim to run faster on this rough terrain, than the whelk could with its heavy shell.
[series of several images]

A trumpet whelk devours one starfish arm in a very short time, and entirely. Perhaps it needs the calcium to build its heavy shell with. In our aquariums we observed an eleven-armed star being eaten, one arm at a time until only one arm remained, and this was eaten too.

f000927: seven-armed stars have a wide variety of colours, from deep purple through grey to brown. They occur from the very north to the very south of New Zealand. Astrostole scabra

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