Yes, the colossal squid is “plump”, also you may notice that it doesn’t usually swim upside down!

The Seven-arm Octopus is so named because in males the hectocotylus (a specially modified arm used in egg fertilization) is coiled in a sac beneath the right eye. Due to this species’ thick gelatinous tissue, it is easily overlooked, giving the appearance of just seven arms.

The short answer is that New Zealand doesn’t (or “didn’t) have more giant species than most places.

Gigantism is a common feature of many animals, not only those found in the deep ocean. However, in terrestrial and coastal habitats readily accessible to man, large animals are easily exploited as a food resource.

As large animals generally have long life spans and slow breeding cycles, most gigantic species have been exterminated within a few generations of their discovery or less!

For example Steller’s sea cow (8 m), a large relative of the manatee which lived on the Asiatic coast of the Bering Sea was exterminated within 27 years of its discovery.

In New Zealand early Polynesians exterminated the giant moa (3m) within 500 years of settlement, giant insects such as weta were rapidly exterminated by introduced rodents, while the vast populations of whales in coastal waters were soon reduced to near extermination by Europeans in the early 1800s before the harvesting became uneconomic.

For many years it was assumed that there was a tendency for some species of invertebrates and other deep-sea dwelling animals to grow to larger sizes than their shallow-water counterparts – a phenomenon known as “deep sea” or “abyssal” gigantism.

However, many marine species living a shallow to moderate depths grow to enormous sizes, so gigantism is not simply a deepsea phenomenon – giant species can only survive if they occur in habitats that are not easily accessible to us!.

Many species of cephalopods, in addition to the colossal squid (6 m) and giant squid (up to 13 m), reach enormous sizes including the seven-arm octopus (9 m), and are found at all depths of the ocean.

Examples of other giant marine animals:
Giant clam (1.2 m) – tropical reefs, 1-20 m depth
Giant isopod (37 cm) – 150 to 2,500 m depth range
Japanese spider crab (4 m) – 300-400 m depth
Colonial salps (4 m) – midwater all depths
Giant jellyfish (10 m) – midwater, all depths
Oarfish (11 m) epipelagic to 1000 m depth
Sunfish (4 m) epipelagic to 1000 m depth
Whaleshark (14 m) epipelagic to 1000 m depth
Blue whale (33 m) epipelagic to 200 m