Subphylum: Crustacea (Crust-a-cea) crustaceans
Insects of the sea
Many people are familiar with prawns, crabs and lobsters. Divers often recognise other larger crustaceans like rock lobsters, shovelnose lobsters, blue swimmer crabs and prawns. The smaller crustaceans are less known.
Coleman's Black Coral crab
Quadrella sp.
The one and only specimen I have ever found, this crab was discovered in a Black Coral bush beneath the stairway leading from the deck to the holds of a wreck at 35 metres at Loloata Island, Papua New Guinea. After exaustive research by the Curator of Crustaceans at the Queensland Museum it was announced as a new species, as nothing resembling it was known from the Pacific Ocean.
(Queensland Museum)
There are around 30,500 species throughout the world. As insects of the sea, their body is encased in an armour-like skin (exo-skeleton). To grow they must shed this skin at various intervals. During this period they are extremely vulnerable and seek places to hide while their new shell-skin hardens.
It is usually possible to identify crustaceans in the field, though colours and patterns vary, external features on juveniles and adults may differ, and sexual dimorphism is often present. Colour photography is an excellent method of recording crustaceans.
They feed on a variety of organisms: bacteria, plankton, sediment, suspended particles, algae, molluscs, fish, worms, other crustaceans and carrion.
The sexes are generally separate and, after mating, the female lays eggs that are carried beneath the abdominal flaps of crabs, on the modified swimmerets (swimming feet) of rock lobsters and shrimps, and on the chests of mantis shrimps. On hatching, the larvae join the plankton and pass through a series of free-swimming stages before settling to the bottom where they metamorphose into juveniles of their particular species.
Crustaceans may be found in almost any habitat in the sea. They live in burrows in sand or mud among rubble, on reefs, in caves and under ledges and rocks. Some bury by day and emerge at night. Some carry shells over their heads and others live in them. Some are permanent swimmers in the vast ocean spaces.
There are species only millimetres in size that are carried about in the water column as plankton, and giants weighing 15 kilograms (33 pounds) that crawl about on rocky reefs 100 metres (330 feet) below the surface.
Eroded Nut Crab
Its amazing what can be found by night diving. This Eroded Nut Crab is a brand new undescribed genus and species photographed at Milne Bay, Papua New Guinea in 2003. All our best efforts at the crustacean dept. of the Queeensland Museum failed to find any trace of it in the published scientific literature.(Queensland Museum)
The Coral - dwelling Hermit Crab Paguritta corallicola was first discovered, photographed and collected in 11 - 1974. It appeared at the time to only live in large colonies in the Infinite astreopora Stony Coral
Astreopora myriophthalma at 20m off Heron Island Great Barrier Reef.
This one coral head had over 23 specimens living in it.
Coral - dwelling Hermit Crab
Paguritta corallicola Lewinsohn,1978
Close up of the Coral - dwelling Hermit Crab Paguritta corallicola.
Dr. Sandy Bruce was resident researcher at the Heron Island Research Station at the time and he had a permit to collect crustaceans and I procured the specimens at his request.
Some years later Dr. Bruce contacted Dr. Lewinsohn the expert on this group in Israel, and the result was that this species was described and published.
Loloata Shrimp
Pontonides loloata Bruce,
First found in my 2002 continuing fauna survey of Loloata Island reefs, this species was named for the Loloata Island Dive Resort in 2005. The Loloata Shrimp Pontonides loloata ( female) lives on Black Coral Sea Whips Cirripathes sp. and the female grows to around 15mm. The male ( not shown) is only 10 mm.
( Queensland Museum)
Grand Shrimp
Periclimenes grandidens Bruce, 2004
Another example of where a species had been known to many divers and photographers for over 30 years, yet it had not been named. Nobody had bothered to collect one and send it off to be identified until I did so in 2003. This is a photograph of the type specimen of what is now known as the Grand Shrimp Periclimenes grandidens from Loloata Island, PNG.
( photo: Neville Coleman) (Queensland Museum)
Mirage Shrimp
Vir sp.
First seen in 1981 this new bubble coral shrimp was not collected till 1989. It was then thought by crustacean taxonomists to be a juvenile of Periclimenes venusta and left at that. In 2001 it was collected again and pointed out that it could not be a juvenile of P.venusta, because it lived on a completely different host.
It was collected again in Nov. 2002 and we now know that it is really a Bubble Coral Shrimp Vir sp. and it is only found on Lichtenstein's Bubble Coral Physogyra lichtensteini. ( Queensland Museum)
Crazy Sea Whip Shrimp
Pontonides asperilatus Bruce,
Only found on the Black Coral Sea Whip Cirrhipathes sp. this rather indistinctive new species had remained undiscovered for 35 years. It was not recognised in any of the previous expeditions and fauna surveys and was described in 2005.
However, now that its image and host have been published, Pontonides asperulatus will just become another species making up Loloata's known marine life.
( Queensland Museum)
MORE SPECIES BEING ADDED AT REGULAR INTERVALS