Their numbers swell into the tens of thousands. A crab spider has eight eyes, and it can still get hold of a prey from a few centimeters away. When solitary, these crabs are often hard to spot; algae, sponges and sea squirts set up shop on their shells and provide excellent camouflage. The gathering also attracts predators such as sting rays and even sharks. The body may grow to a size of 40 cm (16 in) in carapace width and the whole crab can weigh up to 19 kilograms (42 lb) —second in mass only to the American lobster among all living arthropod species. It’s not just enemies in the water the crabs need to defend against. As the name suggests, these crabs are massive. Bayplay Their mission: seek shelter in the safety of the sandy shallows and avoid encounters with the enemy … winged giants fashioned with mouths like crushing plates and sharp-beaked birds that swim. When its legs are stretched out, the spider crab can reach a spread of one foot. When startled, it will wave its pincers over its head in a warning gesture. Like most crustaceans, a hard suit of armour protects these soldiers but, while it protects the crabs, it doesn’t allow them to grow. ‎Each winter, thousands of spider crabs rise up from the depths of Bass Strait to gather for one of the world’s most extraordinary natural spectacles. To do this, they secrete a special enzyme that separates the old shell from the underlying skin, while a new soft, paper-like shell is developing beneath the old one. On our 2019 photographic tour of temperate Australia, Mornington Peninsula, Victoria, was our first stop. For many years these mass aggregations went on relatively unknown to the wider public until in recent years films, such as David Attenborough’s Blue P… Also known as the portly spider crab or the nine-spined spider crab, the common spider crab is a long-legged and slow-moving crustacean that covers itself in algae and small debris as a defense against predators. It transforms the turquoise waters of the Mornington Peninsula into a moving sea of orange that blankets the shallows. Conclusion. The larvae must find their food, however, they are provided with enough yolk that allows them to continue living for a while. Email: bookings@bayplay.com.au. Young hatch from eggs that are bright orange-red when laid but turn brown during development, which takes about 25 days. Simply float on the surface and watch in awe as the seemingly chaotic events unfold below, with these long-legged crabs as far as the eye can see. Another less popular theory for the mystery of the giant spider crabs’ march is that by converging together, they increase their mating success, as crabs can only mate when they moult. It has two teeth toward the front on either side of the carapace and a notch along the middle of the carapace. And the great news is that they are plentiful, easy to catch, and very easy to cook. Ring the local dive shops for the latest updates on the crabs’ movements. The survivors retreat back into the depths of the bay. Boiled or baked, spider crab is truly divine. Tel: (800) YOUR-BAY (968-7229) Shop 5, 7 Thamer Street, Rosebud West (R.P. The common spider crab has a khaki-colored, triangle-shaped carapace (shell) that measure about four inches front to back and features a median row of nine low spines (which differentiate the creature from the six-spined spider crab). Fax: (410) 267-5777, © 2021 Chesapeake Bay Program All Rights Reserved Their weapons: swollen claws. The March of the Crabs Vol. 2385 Point Nepean Road, Rye It’s a phenomenon that needs to be seen to be believed – and anyone can. What we do know is that this natural wonder is unique to Victoria and occurs as the warm waters cool between late March and June. The Spider Crab march is an amazing visual experience and resembles scenes from a science fiction film. One person’s all-time dive is another person’s nightmare. Its eyes are on stalks located at the front corners of its body. The victim is turned on its back, missing a couple of legs and helplessly twitching with those that remain. Covered in seaweed and sponges, a mass of legs crawling this way and that, they pile over the top of one another in a hectic battle for position. Through out the cycle the crabs often moult their shell and at times mass “die offs” of Spider Crabs can be seen. Have you ever tried spider crabs? Email: info@idcscuba.com.au. Phone: (03) 5985 8722 Just as quickly as they arrive, the orange army soon disappears back into the depths of the bay, so mark the dates in your diary so you don’t miss out. Email: diveshop@scubadoctor.com.au. It will often feed on large starfish. When its legs are outstretched, the common spider crab can reach a spread of up to one foot, while males grow larger than females. Spider Crab. The spider crabs walk over each other in a huge mound while they try to shed their shells 6 The new series of Blue Planet II continues with episode five TONIGHT, Sunday, November 26 at 8pm (Photo courtesy of joo0ey/Flickr CC BY 2.0), The carapace (shell) of the common spider crab features a median row of nine low spines. to witness the iconic giant spider crab moulting aggregation! Found from Nova Scotia to the western Gulf of Mexico; inhabits the brackish and salty waters of the Chesapeake Bay from Washington, D.C., to the Bay's mouth. Spider crabs belong to a group known as "decorator crabs": the crab's main defense against predation is ability to camouflage itself with various spines and tubercles, algae, debris and small invertebrates. They have been observed molting in large "pods" in the fall, hibernating in dense patches in the winter and mating in large groups in the spring. Do you have any other spider crab recipes you like? Every year, an army of spider crabs gathers in Melbourne’s Port Phillip Bay ahead of the annual winter moult. As the name suggests, these crabs are massive. As the water cools from the sweltering summer heat these soldiers, with their orange armour-plated uniforms, emerge from the depths and advance on the sandy shallows. Privacy Policy, Chesapeake Bay Program Phone: (03) 5984 1799 They continue to sit in their spots and wait for the preys to walk by. Promotional or other discounts may apply from time to time. They’re harmless and the entire family can enjoy the spectacle. Speaking of spiders, the spider crab thankfully doesn’t look like the frightful arachnid of your nightmares. 3770 Point Nepean Road, Portsea In New Horizons, it appears most frequently between 4am and 9pm. Its shell is often ornamented with various spines and tubercles and clothed in algae, debris and small invertebrates held in place by hook-like hairs. Between May and July each year, tens of thousands of spider crabs march into the shallows of Port Phillip Bay to shed their shells. Diving is the only way of capturing it. Seasonal appearance: All year. For example, Australia's Christmas Island celebrates the landing of the (much smaller and cuter) red crabs in late November-early December. (Ken-ichi Ueda/Flickr), Sensitive tasting and sensing organs located on the tips of the common spider crab's walking legs allow the sluggish scavenger to identify food in the water or mud as it walks. It’s an army like no other and they march not in unison, but in an organised chaos on eight long legs. Limited. 3: The Revolution of the Crabs … Phone: (03) 5984 0888 3755 Point Nepean Road, Portsea Terms of Use | Spider crabs, which have thick, rather rounded bodies and long, spindly legs, are generally slow-moving and sluggish. Nodder/Wikimedia Commons). Try asking people about spider crabs and you will get varied answers. 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