crustaceans 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.
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.
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.
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.
f037829: the triangle crab (Eurynolambrus australis)
is nocturnal. It has a triangular body and strangely shaped legs. Blue
molluscs 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).
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.
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.
f048910: the clown doris (Ceratosoma amoena) is perhaps
New Zealands' most common sea slug.
f037829: the gold-ribbon doris (Chromodoris aureomarginata)
is always clean white with a golden margin.
f037835: the gem nudibranch (Dendrodoris gemmacea,
D. dennisoni) is quite ornate, with brown and blue and elaborate gills.
f037905: the fireslug (Janolus ignis) is nocturnal,
coming out at night. Its colour ranges from red-brown to deep red to orange.
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
f041437: the largest snail in New Zealand is the trumpet
(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.
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.
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.
cnidaria 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.
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.
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.
f052508: Jewel anemones (Corynactis haddoni, C. australis)
have gaudy colours that repeat in patches as each patch consists of cloned
f049718: closeup of jewel anemones (Corynactis haddoni,
C. australis) shows that their tentacles end in rounded tips.
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.
f051437: closeup of zoanthid polyps shows that they are joined
at the base, which acts like a smothering clump.
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.
f052504: a close-up of a colour variant of the cup coral
rubrum) . These animals are best viewed during a night dive when they
are fully extended.
f030537: closeup of the tip of a mauve gorgonean fan () shows
that its skeleton is yellowish and its young polyps white rather than mauve.
f041324: closeup of mauve polyps of a mauve gorgonean fan.
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.
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
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
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
f042717: beadlet coral (Primnoides sp.) begins
at about 40m depth.
f043408: closeup of beadlet coral polyps fully extended (Primnoides
f043211: hydroid trees (Solanderia sp.) are usually
found in shallow water. They are tough.
f034921: lush growth of bushy red hydroid firs, orange bushy
bryozoans, white snowflake sponges and a pink Aplysilla encrusting sponge.
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.
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.
f025905: blue star seasquirt (Asterocarpa coerula)
is one of the most common individual seasquirts and is also found in coastal
f041424: small glassy flask seasquirts (Pycnoclavellina
sp.) grow fast and don't live for long.
f038031: pink mushroom seasquirt (Hypsistozoa fasmeriana)
with many seasquirts sharing a common exhaust vent on left.
sponges 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.
f049013: yellow antler sponge (Iophon proximum) is
common in diveable depths.
f019515: various species of orange finger sponge exist. This
is the two-finger sponge (Pararhaphoxya sp.), as each finger branches
f045819: the thin finger sponge (Callyspongia ramosa)
feels like all Callyspongia species, rough and tough.
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.
f048501: Aplysilla sponges look spiky but feel soft and slimy.
This one is not (Dendrilla rosea) which is more plump.
f029008: a pink encrusting Aplysilla sponge (Aplysilla
rosea). Other Aplysilla encrusting sponges are lemon coloured, purple,
brown, grey and black.
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.
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.
f029015: the golfball sponges (Tethya fastigata) of
the Poor Knights are soft and fluffy, unlike those found in coastal waters.
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.
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.
f045906: a grey toilet sponge (Geodina regina) is
a choice spot for fish like demoiselles and scorpionfish.