![spider crab spider crab](https://animalsoftheworld.info/wp-content/uploads/2018/07/Japanese-Spider-Crab-Macrocheira-kaempferi-768x518.jpg)
If that interests you, sign up for Spider Crab Watch updates. Interested people from around the country (and the world) can then analyse the images to help us count spider crabs and identify their predators. This includes underwater surveys, spider crab tagging and the use of timelapse cameras to capture images of spider crabs and their predators at sites where aggregations are expected.Īfter the aggregations, the images captured will be uploaded to a web portal. We’re also using traditional research to solve these mysteries. Photos are not essential but always welcome. Just report the date, time and location of the spider crabs, and answer a few questions. The reef spans the southern part of Australia from New South Wales to Western Australia and Tasmania.įrom counting birds to speaking out: how citizen science leads us to ask crucial questions We welcome sightings from Port Phillip Bay and across the Great Southern Reef, where spider crabs live. The reports will help us determine the habitats and conditions suitable for spider crab aggregations. We’d also love to hear from people who come across discarded spider crab shells on the beach, because that indicates an aggregation occurred nearby. We’re inviting everyone – including divers, fishermen, swimmers and boaters – to report where they see spider crabs, alone or in groups. To better understand spider crab aggregations, a citizen science project called Spider Crab Watch has been launched. Those aggregations don’t seem related to moulting – in fact, we have no idea why they occur! For example, aggregations in late spring, midsummer and early autumn have been reported in parts of Port Phillip Bay and elsewhere Victoria and Tasmania. Most spider crab gatherings seem to occur in winter, but they’re known to come together at other times. why do the crabs aggregate at one location in several consecutive years then not return?.what signals do crabs use to know it’s time to come together?.For instance, an aggregation was reported this year on the western side of Port Phillip Bay.īut there’s still so much we don’t know about spider crabs, such as: Historically, most winter sightings have been reported on the Mornington Peninsula – particularly near the Rye and Blairgowrie piers.Īnecdotal evidence suggests the gatherings can also happen elsewhere. Spider crab aggregations have been officially reported along the Victorian and Tasmanian coasts. Elodie Camprasse Plenty of mysteries to solve Soft crabs are thought to take refuge in the middle of the piles, protected by crabs yet to moult.Īfterwards, spider crabs return to deeper waters and their solitary lives, leaving the seafloor littered with discarded shells.Ī tiny wasp could save Christmas Island's spectacular red crabs from crazy antsĪ freshly moulted spider crab, left, next to its old shell. The crabs stay together until their new hard shells form, which probably takes a few days. Once together, spider crabs shed their old shells in a synchronised act thought to take about an hour. But they’re most visible to humans when they congregate near shore in winter, and occasionally at other times of year. Spider crabs are believed to be widely dispersed in deeper waters.
![spider crab spider crab](https://www.visitsealife.com/muenchen/media/gz3hlkde/japanische-seespinne2.jpg)
They can reach 16cm across their shell and 40cm across their legs, and are commonly known as great spider crabs. Southern Australia’s spider crabs ( Leptomithrax gaimardii) are usually orange to red-brown. Julian Finn/Museums Victoria Safety in numbers There’s still much to learn about spider crabs. But despite all this attention, scientists know very little about these quirky creatures. The spectacular gatherings attract tourists from interstate and overseas and have even been featured in a BBC documentary. That’s thought to be one reason they clump together in such big numbers – to keep each other safe.
![spider crab spider crab](https://1.bp.blogspot.com/-BhFB1wwOfQk/T85uCGDUCUI/AAAAAAAACOo/jLC8j39veH0/s1600/DSCN6571.jpg)
This moulting process leaves crabs clumsy and uncoordinated, making any escape tricky.
#Spider crab free#
They must break free from their shells, expand their soft flesh and harden a new shell – all while dodging hungry predators on the hunt for a soft, easy meal. These fascinating crustaceans are on a risky mission – to get bigger.Ĭrabs cannot simply grow like humans and other soft-bodied creatures. They form huge underwater piles, some as tall as a person.
#Spider crab series#
Am I not pretty enough? This article is part of The Conversation’s series introducing you to little-known Australian animals that need our help.Įvery winter in shallow waters off Australia’s southern coast, armies of native spider crabs appear in their thousands.