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Beach Mysteries

A walk along the beach following high tide or a storm can be rewarding, although sometimes rather sad, depending on what has been washed up. For the most part findings consist mainly of shells but by keeping your eyes peeled, some interesting items can be observed and a few of these are given below. Storms can cause devastation for some creatures, particularly sea birds and to a lesser extent Cetaceans (whales and dolphins) so please report. Forms and contact details are given under the Research tab.                     


Bluebottle  Physalia spp

Not every summer but most, there is mass strandings of Bluebottles. Often called Jellyfish, they are actually a group of organisms each with a particular part to play in ensuring its survival and are termed Siphonophores.

Unlike true jellyfish which are mobile in their own right, Bluebottles have no mechanism to achieve this and rely on the wind for movement.

The sting of this species can be quite painful and care should be taken when a "bloom" comes ashore.

Wikipedia-Portuguese man-o-war


Ram's Horn Shell  Spirula spirula


Although this seems very shell-like, it is in fact the internal flotation mechanism of a species of deep-water squid. This is a tiny species, reaching a length of 45 mm and living at depths of up to 1000 m.

These shells are extremely light and very buoyant, floating on the surface they are carried on the ocean currents and turn up in their hundreds on beaches.

The live squid is capable of emitting a green light from a photophore (cell) located at the tip of its mantle.

Wikipedia-Ram's Horn Shell


By-the-wind Sailor  Velella velella

This is another species of Siphonophore which is periodically washed up on local beaches  at certain times of the year but not in great numbers as with Bluebottles.

A thin semicircular fin is set diagonally across the float and this acts like a sail which catches the wind and moves these creatures over great distances.

The sting of this species is not that strong but handling should be avoided.

Jellywatch-Velella velella


Kōpūwaitōtara/Porcupine Fish  Allomycterus pilatus

One of the more unusual sights seen around the tide line is this heart-shaped structure. It is the swim bladder of the Porcupine Fish. Occasionally the intact body of this spiny fish is also found. 

Porcupine Fish are a more common species in northern Aotearoa New Zealand than in the south. It is a species frequenting depths of up to 100 m.

They are able to inflate their body when threatened and if found on the beach, avoid as they contain a toxin.

iNaturalist-Porcupine Fish

 Ngaokeote/Scarlet Tubeworm  Galeolaria hystrix

One of the most unusual items you may be lucky enough to find on the beach appears to be either a piece of coral or some cement and its hardness would seem to indicate that it could be the latter.

If you look closely at the texture it consists of a lot of bumps with some holes at one end, some of which appear to have tube-like structures at the entrance.

These are formed by Scarlet Tubeworms which build calcareous tubes to live in and often fuse together


Sambar Deer  Rusa unicolor

This species of deer is only found on the North Island and the Manawatū/Whanganui region is one of two strongholds for this species, the other being Hawke's Bay.


Tracks can often be seen in the sand and is generally the only sign these animals are in the area. It is thought they some times cross the river a low tide..

They are an introduced species and in their homeland of Southeast Asia they are classified as vulnerable.

Wikipedia-Sambar Deer

blue shell for web.jpg
Dwarf Janthina  Janthina exigua

Among the many shells of various types and colours is sometimes seen this unusual shell. Looking more like that of a land snail it is a species of marine snail.  This is the smallest of the five species at around 15 mm.

The unique colouration serves a specific purpose and this is to do with its lifestyle of living on, and feeding off Bluebottles and By-the-wind sailor.

They are capable of free-living by producing a raft of bubbles. More details are given in the link below. 

Mussel Beard

Quite often when you find mussel shells on the beach they may have attached to them what appears to be hair-like structures. These appear similar to a beard which givens them their common name.

The technical term for these is byssus and they are formed by many species of bivalves (mussel family) and are secreted along sections of the shell.

They a used to anchor them to a surface such as rocks where they create a hold-fast in strong currents. 

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