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Alan Jamieson with one of the supergiant amphipods. Photo copyright of Oceanlab, University of Aberdeen, UK. |
Amphipods are a type of crustacean that are particularly common in the deep sea and are found in greater numbers in the depths of the oceans. Most deep sea amphipods are about 1-1.5 inches (2-3 cm) long, with the exception of the slightly larger ‘giant’ amphipod found in Antarctica which grows to 4 inches (10cm).
Now however, scientists have been stunned to discover what has been dubbed a ‘supergiant’ amphipod in waters north of New Zealand that clearly dwarfs the Antarctic ‘giant’. The newly-captured specimen measures 28cm – nearly 1 foot long and ten times that of a typical amphipod. A even bigger specimen estimated at 13in (34cm) was also observed on film.
The discovery was made during a joint UK and New Zealand expedition to the Kermadec Trench, north of New Zealand, led by scientists from the University of Aberdeen in Scotland and the National Institute of Water and Atmospheric Research (NIWA). Also aboard NIWA’s research vessel Kaharoa were researchers from the Museum of New Zealand Te Papa Tongarewa and Whitman College, in America.
Using specially built ultra-deep submergence technology designed by the University of Aberdeen’s Oceanlab, the team deployed a camera system and a large trap at depths ranging from 22,700-32,500ft (6900 to 9900m).
Searching for snailfish
At depths of approximately 23,000ft (7000m), the team was hoping to recover specimens of deep sea snailfish which they have photographed before, but have not been captured since the early 1950s. Voyage leader, Dr. Alan Jamieson from the University of Aberdeen’s Oceanlab, said: "The moment the traps came on deck we were elated at the sight of the snailfish as we have been after these fish for years.
"However, seconds later, I stopped and thought ‘what on earth is that?’ whilst catching a glimpse of an amphipod far bigger than I ever thought possible. It’s a bit like finding a foot long cockroach!"
‘Supergiant’ is a term coined by American scientists in the early 1980s after a few large specimens were caught off the Hawaiian Islands. Despite a few infrequent findings in the 1970s, the supergiant amphipod has not been reported since and had faded into the realms of rare and mysterious deep sea creatures - until now.
This latest discovery represents both the biggest whole specimen of a supergiant ever caught, and the deepest point at which they have ever been found. Seven specimens were captured in the trap and up to nine were photographed gathering around the camera system.
On the move
Dr Ashley Rowden, from NIWA in Wellington, said: "It just goes to show that the more you look, the more you find. For such a large and conspicuous animal to go unnoticed for so long is just testament to how little we know about life in New Zealand’s most deep and unique habitat."
Dr Jamieson added: "The surprising thing is that we have already been to this deep trench twice and never come across these animals before. In fact, a few days after the discovery, we deployed all the equipment again on the same site and we didn’t photograph or capture a single supergiant; they were there for a day and gone the next."
Now the challenge for the team is to determine whether these new specimens belong to the same species as those from Hawaii, and then try to establish why, out of the hundreds of species of deep-sea amphipods, these particular ones have become so large.