Octopus and Squid – Cephalopods on the South Coast

It is said that the great Maori navigator, Kupe, set out from Hawaiki in a large canoe to hunt down a giant octopus, Wheke o Muturangi, which was stealing fish from his tribe. The chase was long and hard, and the wheke took shelter in Raukawa Moana (Cook Strait). Kupe killed the wheke with a head blow and placed its eyes on Nga Whatu (the Brothers).

Octopus, cuttlefish and squid are cephalopods, related to molluscs, though clearly greatly divergent from the snails and bivalves we know today. Cephalopods are a key group of predators in both octopus IBMEC

Octopus at Island Bay Marine Education Centre Photo: IBMEC

oceanic and nearshore habitats. Most have soft bodies, numerous arms (eight for octopus) and two tentacles (squid), well-developed eyes, and complex life cycles and behaviours. Their size ranges from small squid, around 5 cm in length, to giant squid, known to reach 13 m length. Squid suckers are edged with hooks; octopus suckers have no teeth or hooks, each sucker being a strong suction disc. Most cephalopods have a short life cycle – 12 to 18 months, and are semelparous i.e. they usually die after spawning. Living cuttlefish are not found in NZ seas.

AN OCTOPUS AT WELLINGTON.- Taranaki Herald 1880 
Stranded high and dry on Island Bay, Wellington, was a monster, the very aspect of which was appalling, and (says the Chronicle) kept everyone at a respectful distance. Were such horrible spectacles common visitants (and we believe that old Ocean can boast of a good many of them), neither bathing, rowing, or any other aquatic sport would be possible. The creature in question measured ten feet from head to tail, and some of its tentacles extended to 25 feet, none being less in dimensions than three actual yards. Its tail was so powerfully constructed- that it would not be possible for any ordinary boat to live within a dozen yards of it. The sockets of its eyes were as large as saucers, and glared with a ferocity singularly awful. An octopus of this kind adds a new terror to existence, and should cause the pleasant little inlet known as Island Bay to be carefully avoided. Those who have ever felt the clammy and cold touch of a devilfish can alone realise the horror of its hellish embrace. The secrets of the briny deep are most wonderful.  
 

Octopus

Of the 42 species of octopus known from New Zealand, only a few are commonly encountered. Octopus live mainly on the sea floor. However, small specimens of the common octopus (Pinnoctopus cordiformis or wheke) and the fist-sized Octopus huttoni can often be found in tidal rock pools. As wheke grow, they venture into subtidal reefs. Reaching over 1 metre in length and 9 kilograms in weight, they are among the largest predators on the reef. They feed on crayfish, crabs and shellfish.

The octopus does most of its hunting at night. It emerges from its rocky lair to seek crabs, crayfish, and molluscs, which are its favourite foods. The octopus catches most of its prey by stealth. Having changed colour to blend in with its surroundings, the well-camouflaged octopus waits for prey to pass by and then seizes it with its long arms. The arms are powerful and flexible, with two rows of suckers that help it grip its slippery prey. The octopus then stuns its victim with a secretion of nerve poison. To stalk lobsters and other dangerous prey, the octopus squirts ink into the water to form a screen. Hiding behind the dark cloud, it creeps up on its victim and grabs it from behind.

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Red octopus, perhaps angry with photographer Stephen Journee

If the octopus’s prey is hard-shelled, the octopus punctures the shell by drilling with its tongue, which is covered in small, sharp teeth. The octopus’s predators include moray and conger eels, dolphins and sharks. Whenever possible, the octopus will escape from its predators by shooting a jet of water through its body to create a burst of speed. An octopus has a hard beak, with its mouth at the center point of the arms. Octopuses have no internal or external skeleton (although some species have a vestigial remnant of a shell inside their mantles), allowing them to squeeze through tight places. Octopuses are among the most intelligent and physically flexible of all invertebrates.

Often, however, the octopus avoids detection completely. It can change its body colour and texture so perfectly that it can virtually disappear. The coloured pigment in its skin can be concentrated or diluted, forming stripes and patterns that blend into the environment. The octopus’s ink sac also helps it avoid attack. It releases a disorienting black cloud that is accompanied by another secretion to dull the attacker’s sense of smell.

Octopus are especially clever with their long tentacles. Being able to unscrew lids from bottles and jars, apparently predict the winners of football matches, and snatch cameras from divers! http://www.stuff.co.nz/life-style/cutestuff/3590839/Octopus-flees-with-camera

Squid

Many people have seen the preserved colossal squid at Te Papa, which was 8 to 10 m long when caught in the Ross Sea. Squid on the Wellington South Coast are not usually as big as that, and the biggest local squid almost certainly come up from a good depth in the Cook Strait.  Residents of Houghton Bay found a giant squid washed up on the shore in 2010, thought to have been attacked further out to sea. 

broad squid seafriends

Broad squid  Photo: Seafriends

Squid are fished along the coast and inside Wellington Harbour, being known to blast aluminium-staining ink in the vicinity of spear fishers. While there are many different squid species in NZ waters, on the South Coast divers may see arrow squid (Nototodarus sloanii) and broad squid (Sepioteuthis bilineata). Broad squid have a body up to 30 cm in length. The arrow squid is also called the Wellington flying squid and it much favoured as food for marine mammals, diving birds and yellow eyed penguins. They are heavily fished around the Subantarctic Islands, and fishing presents a high risk to the critically endangered NZ sea lion. 

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Broad squid at the Snorkel Trail  Photo: M Hosking

Broad squid have a body up to 30 cm in length. Small broad squid are often seen at the surface around the Snorkel Trail looking for small fish such as triplefins to eat.

Sources and References:

http://www.octopus.org.nz/factsheets/octopus.html

http://www.seafriends.org.nz/indepth/octopus.htm