49 — Lined whelk, Buccinulum linea

Buccinulum linea laying eggs,
Tamaki Drive, 1/09/16.

Buccinulum linea laying eggs,
Tamaki Drive, 1/09/16.

Buccinulum linea, Tamaki Drive, 1/09/16.

The lined whelk, Buccinulum linea * is a small (~35mm) gastropod, which is endemic to New Zealand. They live inter-tidally and down to a couple of dozen metres depth and are common if you know where to look. They are thought to feed on compound ascidians (although I can't remember where I read that...), so if you look for a place where there are conditions that compound ascidian like, then chances are you'll also find lined whelks.

The first two pictures show a lined whelk laying eggs. The eggs are quite small when they are first laid (otherwise, where would they all fit?), but quickly expand by absorbing water.

There are many species of these whelks in New Zealand, and they can be quite a challenge to identify, as some of them are superficially quite similar-looking. Consequently, there are a few mis-identifications on the web.

*(Martyn, 1784)











More info:

http://www.mollusca.co.nz/speciesdetail.php?speciesid=1072&species=Buccinulum%20linea

48 — Ecklonia holdfasts

Ecklonia radiata holdfast, Mount Beach, 1/10/16.

Many kinds of seaweed attach to rocks/substrates with a holdfast and over time these can become encrusted with all sorts of marine life. These holdfasts can represent micro-habitats for a variety of marine life. However, sometimes the encrustations get so large that the seaweed can no longer stay attached and gets washed off.

This is a bit of the holdfast of the kelp Ecklonia radiata. There are quite a few different wee animals to be seen... The small red things are a type of ascidian (sea squirt). The beige-coloured finger-like projections on the left are a type of sponge, and the small twig-like things are the stems of some kind of thecate hydroid.

Normally there would also be gastropod snails and various small crustaceans. But these mobile animals, which would normally make a holdfast their home, seem to know when its is doomed and make good their escape.

47 — Xenophora neozelanica

Xenophora neozelanica, Sulphur Point dredge,
Tauranga Harbour 1973.

Xenophora neozelanica, Sulphur Point dredge,
Tauranga Harbour 1973.

Xenophora neozelanica, off Mayor Island,
Bay of Plenty, 1971.

Xenophora neozelanica, off Mayor Island,
Bay of Plenty, 1971.

Xenophora neozelanica, off Mayor Island,
Bay of Plenty, 1971.

Carriers shells are a really unusual kind of sea shell, since they pick up other pieces of shell, rock, coral or pretty much anything and stick it on their own shell. They come from the family Xenophoridae, which actually means 'foreign carrying'. They get up to about 60mm across the base and are often completely covered in living marine life.

There are species found around the world, but the one pictured here is the New Zealand carrier shell (Xenophora neozelanica Suter, 1908). They are found on the continental shelf down to nearly 200m, but only around the northern half of North Island. There is also a sub-species found at the Kermadec Islands. They're not a seashell that gets seen all that often, as they live a little too deep to be washed in by storms.

Often the material placed on the outside of the carrier shell is reflects its immediate environment; if they are around shelly material they will attach shells, if it's gravel, then they'll attach gravel. It is thought that carrier shells always place bivalve shells with the inside facing outwards to display that the bivalve is dead.

































More info:

http://www.deepseanews.com/2013/06/the-masters-of-bling-carrier-snails/

https://www.niwa.co.nz/blogs/critteroftheweek/164

46 — Sand dollar urchin, Fellaster zelandiae

Fellaster zelandiae Pilot Bay,
Mt. Maunganui, 10/16.

Fellaster zelandiae, Mount Beach,
Mt.Maunganui, 27/7/18

Fellaster zelandiae, coming up through the sand
at Cheltenham Beach, Auckland, 17/6/18.

A dead F. zelandiae Mount Beach 16/7/18.

The sand dollar Fellaster zelandiae (Gray, 1855) is usually seen washed up as broken segments (a bit like small pizza slices), so people don't usually see what they really look like alive. Sand dollars are a type of sea urchin, but an extremely flattened one, with very short spines.

They're deposit-feeders, which means they eat sediment, digest any organic matter they find and then excrete out the rest.

Fellaster zelandiae is found on the east coast of Australia, Tasmania, and throughout North Island down to the upper half of the South. These are about 10cm across.

These sand dollars display what's called pentamerous symmetry (having parts arranged in groups of five), a feature common to most echinoids.





















More info:

NIWA echinoderm identification guide

https://marineinfo.otago.ac.nz/publications/cid/707/

45 — Snake's tail brittle star, Ophiopsammus maculata

Ophiopsammus maculata, Mount Beach,
Mt. Maunganui, July 2018.

Ophiopsammus maculata (Verrill, 1869) is a large purple brittle star found throughout New Zealand. Occasionally seen at them at low tide, they are more common sub-tidally. They have been called snake's tail brittle stars, but this name doesn't seem to be in common usage.

They are quite large and the central disc can be about 50mm across. These examples come from just below low tide around the base of Mt. Maunganui. Overall, they range between 20 and 30 cm across.

Ophiopsammus maculata Mt. Maunganui, 10/16

Ophiopsammus maculata Mt. Maunganui, 10/16

Ophiopsammus maculata Mt. Maunganui, 10/16

More info:

NIWA Echinoderm Identification guide

44 — Octogonal murex shell, Murexsul octogonus

Murexsul octogonus, Kohimarama Beach,
Auckland 2/04.

Murexsul octogonus, Kohimarama Beach,
Auckland 2/04.

Murexsul octogonus, Kohimarama Beach,
Auckland 2/04.

The octagonal murex (Murexsul octogonus (Quoy & Gaimard, 1833)) is so named because when you down on the spire from the above the sequence of varices (growth ridges) makes the shape of an octagon. They are found in shallow water in the north of New Zealand and can have quite spectacularly spiny shells.

This shell is from off Pakiri Beach, north of Auckland. However, it was actually found on one of the inner city beaches at Kohimarama Beach. This is because that beach was having its sand replenished using sand taken from off Pakiri Beach from depths of about 20–30 m.

The ecology of octagonal murexes is not that well known, but it is thought that they predate bivalves by boring through their shells (like other members of the Muricidae). This species used to be seen more often in the Auckland region and Morton & Miller (1968) describe it a being part of the lower intertidal assemblage of gastropod predators. These days they're not seen that often.
















More info:

More pictures: http://www.mollusca.co.nz/speciesdetail.php?speciesid=996&species=Murexsul%20octogonus

Morton, J. E., & Miller, M. M. 1968. The New Zealand Sea Shore. Collins.

43 — Coral anemones, Corallimorpharia

Corynactis australis, Rock pool on Lion Rock,
Piha, 11/15.

Corynactis australis, Rock pool on Lion Rock,
Piha, 11/15.

Corynactis australis, under a rock,
Mt. Maunganui, 2015.

Corynactis australis, from a deep rock pool on
Lion Rock, Piha, 11/15. These covered the walls
 of the pool.

Two deep-sea Corallimorphus niwa Fautin, 2011
 coral anemones from deep-water
on Challenger Plateau, west
of New Zealand, TAN0707, 2007.

Coral anemones are in the order Corallimorpharia, while sea anemones belong in the order Actinaria. The easiest way to tell them from true sea anemones is to look at their tentacles: if the tentacle has a knob on the end, it's a corallimorph not an anemone. Corallimorphs are essentially corals without a calcareous skeleton. However, they do leave a calcareous base under each anemone, which is left behind after the anemone dies.

There is one common species found in New Zealand: the jewel anemone (Corynactis australis, Haddon & Duerden, 1896), which is found at low tide and shallow waters on rocks. They appear to like shady habitats and can multiply by fission, so you can often get large mats of them. Jewel anemones are small (~10–15mm) across the disc, but can be a spectacular range of colours.

There are other species found in New Zealand waters, but these are from in deep-water and are not often seen.











































More info:

https://www.niwa.co.nz/blogs/critteroftheweek/192

https://shapeandtheidea.wordpress.com/2015/10/27/jewel-anemone/

https://en.wikipedia.org/wiki/Corallimorpharia

42 — Micro-molluscs, Pyramidellidae

Unidentified pyramidellids, unknown location,
 New Zealand (shells are ~5mm in length).

Turbonilla sp., unknown location, New Zealand.

These small shells (~5mm) are in the family Pyramidellidae, most probably in the genus Turbonilla. These micro-molluscs are thought to be vampiric ectoparasites: they suck the blood of their hosts. The New Zealand ones can be difficult to identify, as there are many species and their descriptions aren't very helpful. You end up trying to count the axial ribs using a microscope. There are also quite a few species, many of which are yet to be described.

The morphology of the shell is really interesting, as the early whorls (the protoconch) is sinistral (coiled left handed), but the adult shell is dextral (coiled right handed), so the shell changes direction after the first few whorls.

I get the impression that there may be some grey literature regarding these little shells. Grey literature are reports or unpublished non-peer reviewed articles.  Often the material within them is very valuable. An example would be this account in Tane: The Auckland University Field Club Journal. Before the internet this sort of material was difficult to find, so it's really great that much of it is now being made available.

As far as I can tell, very little is known about the possible hosts for the New Zealand species. But it has been speculated that the hosts could be other bivalve molluscs and/or polychaete worms. Probably a research project here for someone...


More info:

https://en.wikipedia.org/wiki/Pyramidellidae