Poor Knights marine reserve
common cliff dwellers
by Dr J Floor Anthoni (2007)

The Poor Knights are very rich in lower organisms that live on the rocky shore, the cliff dwellers. In this chapter only the most common ones can be shown.
  • crustaceans: crayfish, camouflage crabs, hermit crabs
  • echinoderms: for starfish and sea urchins see echinoderms (6p)
  • molluscs: the colourful nudibranchs and some snails
  • cnidaria: anemones, corals, gorgonean fans, bryozoa,
  • sea squirts: only a few of the many species found
  • sponges: there are hundreds of species

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The Poor Knights does not have many crustacean species, and those found are not numerous. This anomaly is caused perhaps because crustaceans release their eggs when hatching, and their larvae need to spend some weeks in the plankton soup. Because larvae are carried away on currents, and currents arriving from the north contain few crustacean larvae, their replacement rate is correspondingly low. This problem is typical of living on or around a remote island surrounded by a large empty ocean.

large crayfish (Jasus edwardsi)
f051135: a large crayfish (Jasus edwardsi) is a rare find nowadays, even though they have not been fished for 20 years. Some very large packhorse crayfish (Jasus verreauxi, Sagmariasus verreauxi) can still be found but juveniles remain absent.
anemone-carrying nocturnal hermit crab (Dardanus arrosor)
f043315: the anemone-carrying nocturnal hermit crab (Dardanus arrosor) is shy and runs fast. It is a large animal and can grow the size of a human hand. Middle Arch and Rikoriko. This one is housed in a light-shelled deep water trumpet whelk.
Peron's seaweed crab (Notomithrax peroni)
f028920: several species of camouflage crab can be found, especially at night. This is Peron's seaweed crab (Notomithrax peroni). Also the lesser camouflage crab (Notomithrax ursus) and the long-armed spidercrab (Leptomithrax longimanus). They are not easy to see.
triangle crab (Eurynolambrus australis)
f037829: the triangle crab (Eurynolambrus australis) is nocturnal. It has a triangular body and strangely shaped legs. Blue Maomao Arch.

The Poor Knights has many species of mollusc, including open water northern arrow squid and broad squid and rarely an octopus, but the most spectacular ones for divers and photographers are the nudibranchs, best found in Middle Arch.

f029404: the fine-lined tambja (Tambja sp.) lives mainly from hydroid firs. Although these two look like different species, they are apparently the same.
f029424: the morose tambja (Tambja morosa) can be jet black with blue, but this one is somewhat greenish. It feeds on bryozoans like the orange stick bryozoa (Steganoporella neozelandica) and the bushy orange bryozoa (Emma triangulata).
Verco's tambja (Tambja verconis)
f029425: Verco's tambja (Tambja verconis) can have a greenish to bright yellow base colour, but its stripes, horns and gills are always bright blue. They feed on the bushy blue Bugula dentata bryozoan firs, bottom left.
sea tiger (Roboastra luteolineata) eating other tambja
f030433: the sea tiger (Roboastra luteolineata) is a voracious predator on other tambja nudibranchs. Here it is seen devouring a fine-lined tambja. The sea tiger is green with bright orange lines.
clown doris (Ceratosoma amoena)
f048910: the clown doris (Ceratosoma amoena) is perhaps New Zealands' most common sea slug.
gold-ribbon doris (Chromodoris aureomarginata)
f037829: the gold-ribbon doris (Chromodoris aureomarginata) is always clean white with a golden margin. 
gem nudibranch (Dendrodoris gemmacea, D. Denisoni)
f037835: the gem nudibranch (Dendrodoris gemmacea,  D. dennisoni) is quite ornate, with brown and blue and elaborate gills.
fireslug (Janolus ignis) is nocturnal
f037905: the fireslug (Janolus ignis) is nocturnal, coming out at night. Its colour ranges from red-brown to deep red to orange.
smooth tiger snail (Calliostoma tigris)
f018311: two species of tiger snail eating away at sponges. The big one is the smooth tiger snail (Calliostoma tigris, Maurea tigris) and the smaller one the rough tiger shell (Calliostoma punctulata, Maurea punctulata)
trumpet whelk (Charonia lampas rubicunda.)
f041437: the largest snail in New Zealand is the trumpet whelk (Charonia lampas rubicunda.) which has several related species. This one is found at the Poor Knights. Trumpet whelks hunt echinoderms like sea urchins and sea stars.
eggmass of northern arrow squid (Notodarus sloanii)
f052307: the diver shows the size of the egg mass of the northern arrow squid (Notodarus sloanii). Although completely transparent, its skin is tough and rubbery. This protects the squid eggs during a critical stage in their development.
broad squid (Sepioteuthis australis)
f049333: the broad squid (Sepioteuthis australis) is found in coastal shallows, but adults move into deeper water. At night they will visit the shore to lay their eggs inside tough white rubber fingers. They are cunning predators. We saw one catch a triplefin - snap, so easily.

The soft-bodied animals with stinging cells look very much like flowers, and are also known as flower animals. They include the free swimming jellyfish, the attached anemones and those who make hard skeletons, such as corals, gorgonean fans, bryozoa and hydrozoa. New Zealand has a high number of these, and the Poor Knights is a hot spot of their biodiversity.

white-tipped anemone (Actinothoe albocincta)
f019107: the white-tipped anemone (Actinothoe albocincta) loves exposed sites not far from the surface. Here it propagates by splitting parts of its foot off. What we look at in this picture is a single organism consisting of many clones.
horse anemone or beadlet anemone (Isactinia tenebrosa)
f051333: the horse anemone or beadlet anemone (Isactinia tenebrosa) lives just around low tide mark and is often exposed at low tide. One finds them on shaded walls in the intertidal zone.
Jewel anemones (Corynactis haddoni)
f052508: Jewel anemones (Corynactis haddoni, C. australis) have gaudy colours that repeat in patches as each patch consists of cloned individuals.
ewel anemones (Corynactis haddoni)
f049718: closeup of jewel anemones (Corynactis haddoni, C. australis) shows that their tentacles end in rounded tips.
zoanthid anemones
f019622: zoanthid anemones are not separate individuals, as they are joined at their base. Zoanthids are invasive species capable of killing their host by suffocating it.
zoanthid anemones
f051437: closeup of zoanthid polyps shows that they are joined at the base, which acts like a smothering clump.
cup coral or fan coral (Flabellum rubrum, Monomyces rubrum)
f019300: this cup coral or fan coral (Flabellum rubrum, Monomyces rubrum) is the only hard coral found at the Poor Knights. It feeds from zooplankton and is usually found in shallow dark places.
Monomyces rubrum
f052504: a close-up of a colour variant of the cup coral (Flabellum rubrum) . These animals are best viewed during a night dive when they are fully extended.
mauve gorgonean fan
f030537: closeup of the tip of a mauve gorgonean fan () shows that its skeleton is yellowish and its young polyps white rather than mauve.
mauve gorgonean fan
f041324: closeup of mauve polyps of a mauve gorgonean fan.
rich rock encrusting life
f034923: gorgonean fans and other bushy cliff dwellers thrive best where they are protected by an overhang or steep wall. The photo shows mauve gorgoneans and bushy orange bryozoans, as well as a variety of encrusting sponges and some stick bryozoa.
rich rock encrusting life
f048705: a male pigfish at an overhanging vertical wall, studded with gorgonean fans and blue-green bushy bryozoans. The rock in-between is covered in matting sponges, particularly the lemon and pink Aplysilla mats.
gorgonean fans
f048711: an overhang studded with purple gorgonean fans, but there are two yellow ones. These are small invasive zoanthid anemones that have invaded a purple gorgonean and now pretend as if they made the coral fan.
dead man's fingers (Alcyonium aurantiacum)
f018118: dead man's fingers (Alcyonium aurantiacum) is a true soft coral whose polyps have eight tentacles. Often these are fully retracted, which makes the blob look like either a sponge or a dead man's fingers.
beadlet coral  (Primnoides sp.)
f042717: beadlet coral  (Primnoides sp.) begins at about 40m depth.
beadlet coral  (Primnoides sp.)
f043408: closeup of beadlet coral polyps fully extended (Primnoides sp.).

hydroid trees (Solanderia sp.)
f043211: hydroid trees (Solanderia sp.) are usually found in shallow water. They are tough.
hydroid and bryozoan firs
f034921: lush growth of bushy red hydroid firs, orange bushy bryozoans, white snowflake sponges and a pink Aplysilla encrusting sponge.
stick bryozoa (Steganoporella neozelandica)
f045532: super macro photo of a stick bryozoan (Steganoporella neozelandica) of which all polyps are out and extended. These polyps are hardly visible without magnification.

sea squirts
Seasquirts can be of the invasive matting type that grow fast and die soon, or of the individual type that can reach considerable age. The Poor Knights has a high variety of seasquirts, and these are often mistaken for sponges. For more seasquirts, see the rocky shore study.

warty seasquirt (Microcosmos kura)
f052403: the individual warty seasquirt (Microcosmos kura) invites other organisms to grow over its skin, thus achieving almost complete camouflage. The photo shows two joined together.
blue star seasquirt (Asterocarpa coerula)
f025905: blue star seasquirt (Asterocarpa coerula) is one of the most common individual seasquirts and is also found in coastal waters.
glassy flask seasquirts (Pycnoclavellina sp.)
f041424: small glassy flask seasquirts (Pycnoclavellina sp.) grow fast and don't live for long.
pink mushroom seasquirt (Hypsistozoa fasmeriana)
f038031: pink mushroom seasquirt (Hypsistozoa fasmeriana) with many seasquirts sharing a common exhaust vent on left.

It would be impossible to parade even the most common sponges here, because there are so many and there are no reference works to easily identify them from, but we are working on this.

yellow antler sponge (Iophon proximum)
f049013: yellow antler sponge (Iophon proximum) is common in diveable depths.
two-finger sponge (Pararhaphoxya sp.)
f019515: various species of orange finger sponge exist. This is the two-finger sponge (Pararhaphoxya sp.), as each finger branches in two.
thin finger sponge (Callyspongia ramosa)
f045819: the thin finger sponge (Callyspongia ramosa) feels like all Callyspongia species, rough and tough.
various rough finger sponges (Callyspongia sp.)
f048722: various rough finger sponges (Callyspongia sp.). In the foreground flat fingers, and behind it a rough organ sponge (C. latituba) and another rough finger sponge.
thin dendrilla sponge (Dendrilla sp.)
f048501: Aplysilla sponges look spiky but feel soft and slimy. This one is not (Dendrilla rosea) which is more plump.
pink encrusting Aplysilla sponge (Aplysilla rosea)
f029008: a pink encrusting Aplysilla sponge (Aplysilla rosea). Other Aplysilla encrusting sponges are lemon coloured, purple, brown, grey and black.
yellow boring sponge (Clione celata)
f025827: the yellow boring sponge (Clione celata) is quite robust because it drills shallow holes in the rock from which it cannot be removed. It is very hardy and is found at all depths.
grey nipple sponge (Polymastia sp.)
f017731: nipple sponges like this grey nipple sponge (Polymastia sp.) feel fluffy and not slimy. When touched, they contract. Several Polymastia species exist, in colours varying from bright yellow to orange to brown to grey.
golfball sponge (Tethya fastigata)
f029015: the golfball sponges (Tethya fastigata) of the Poor Knights are soft and fluffy, unlike those found in coastal waters.
calcareous flask sponges (Leucettusa lancifer)
f032601: calcareous flask sponges (Leucettusa lancifer) feeling hard to the touch, surrounded by a thick mat of encrusting sponges. They are brittle and easily broken.
massive grey sponge (Ancorina alata)
f048016: the massive grey sponge (Ancorina alata) is very common and robust, occurring both inshore and offshore and in degraded environments. Here it is recovering from partial decay, visible as white.
grey toilet sponge (Geodina regina)
f045906: a grey toilet sponge (Geodina regina) is a choice spot for fish like demoiselles and scorpionfish.