Kodiak Daily Mirror - Giantism evolves in Ocean Depth and Cold
  
Giantism evolves in Ocean Depth and Cold
by Switgard Duesterloh
Jul 18, 2014 | 102 views | 0 0 comments | 40 40 recommendations | email to a friend | print
I have never heard of Werner Herzog before. However, when I was looking for a fitting quote to start this article with, it was his quote I found best suited: “What would an ocean be without a monster lurking in the dark? It would be like sleep without dreams.”

I do not usually refer to any ocean creature as a monster, because I think that every life form has evolved to succesfully suit its habitat. I am always fascinated by how many ways nature has devised for life to thrive under the various conditions of our planet and rather than disregarding life forms as ugly or monsterous I think it worthwhile to study their unique attributes and wonder how and why they have evolved.

On a recent wildlife tour of Kodiak I showed some visitors my collection of ocean treasures including clam, cockle and scallop shells, hairy triton snails, giant barnacles, and some crab molts. If the guests are familiar with these animals from their homes in Europe or the lower 48, they are usually impressed by the size of our Alaskan specimen. The plate sized scallop shells, the soup bowl sized butterclam, the boot sized gumboot chiton and the giant barnacle shell that you could use as a small planter, they all convey the same message: we grow things big here.

The examples don’t end there. Animals that are common in many parts of the ocean tend to be larger here. For example, Bering Sea herring are on average almost twice as big as the herring I used to know from the Baltic and North Sea where I grew up. The octopusses I used to watch when diving in the Mediterranean Sea were also half the size of the giant Pacific octopus found here. Alaska is home to one of the largest kelp (bull kelp), the largest species of sea cucumber (California cucumber), the largest sea star (sunflower sea star), the second largest crab (red king crab), the largest halibut (Pacific halibut), and the largest Sea lion (Steller sea lion). Why do we grow them so big here?

One of the answers to that question is certainly the combination of nutrients upwelling with water from the ocean depth and reaching the sunlit surface. The growth of marine algae forms the base for a productive food chain. A second reason are the cold temperatures. Though it seems counterintuitive, cold temperatures support giantism.

Usually, biological processes slow down when the temperature is lower and speed up when the temperature is higher. However, there is a clear correlation between the occurrence of very large animals and consistently cold temperatures. A 2006 research program to census the life in the Antarctic ocean found an astonishing number of very large animals. The deep sea, where it is consistently cold, has the largest invertebrate known, the giant squid, which can grow to 47 feet. It is also home to a giant isopod and several big crab species including the Japanese spider crab, which grows to a leg span of 12 feet and can weigh 42 pounds. So how do they grow so big?

If temperatures are low and growth rates are slow, cells have a tendency to live longer and get bigger. Since animals like some crabs and squid can grow as long as they live, they can get pretty big. For reproduction and the survival of the species it is good to have big mothers, because they can produce more eggs.

While stories of the giant kraken are still in the realm of myths, the giant squid might have spurred some of those tales. For many years, there were never scientifically documented and photographed specimen of those huge squid, but since the turn of the century several giant squid have been found washed up, caught in fishing nets, measured, preserved and even filmed. Thus the giant squid, once a member of the unknown and mysterious, has become just another catalogued example of giantism among deep sea species. Nonetheless, every year new discoveries reveal ocean life forms no one knew existed. I feel blessed to live in a time where there are still many discoveries to be made, because as Werner Herzog implies, there is a certain allure to the unknown monsters lurking in the dark.

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