Australia is home to a fascinating mix of arachnids and crustaceans that often get confused due to their names—crab spiders and spider crabs. While crab spiders are small, camouflaging hunters found on plants, spider crabs are large marine crustaceans known for their migrations. Adding to the confusion are myths about “coconut crab spiders” and “giant crab spiders.” This article explores the real species, their appearances, behaviors, edibility, and the truth behind these popular misconceptions.
Types of Crab Spiders in Australia
Australian Crab Spider (General Overview)
Crab spiders in Australia belong mainly to the family Thomisidae. They are named for their crab-like stance and sideways walking movement. Unlike web-building spiders, they are ambush predators that rely on camouflage, often blending perfectly into flowers and plants. These spiders play an important role in controlling insect populations across gardens, forests, and grasslands.
Giant Crab Spider in Australia
The term giant crab spider in Australia usually refers to larger members of the huntsman family (Sparassidae), sometimes confused with true crab spiders. These can reach leg spans up to 15 cm and are often spotted inside homes or sheds. Though intimidating in appearance, they are generally harmless and feed on cockroaches and other insects, providing natural pest control.
Color Variations and Appearance
Australian crab spiders display impressive adaptations in color:
- White Crab Spider – Often found on pale flowers, using camouflage to capture pollinators.
- Yellow Crab Spider – Blends with bright blossoms like daisies or sunflowers.
- Green Crab Spider – Matches leafy plants and shrubs.
- King Crab Spider – A colloquial name sometimes given to large species with striking markings.
- Crab-like or Crab-looking Spiders – General descriptors used for their sideways movement and flattened body shape.
These variations highlight their survival strategy—camouflage for ambushing prey and avoiding predators.
The Misconception About Coconut Crab Spiders
Are There Coconut Crab Spiders in Australia?
Despite the frequent mention of “coconut crab spiders,” no such species exists in Australia—or anywhere else. This term likely arises from confusion between the coconut crab (Birgus latro), a giant terrestrial crustacean, and the crab spider. Coconut crabs live on islands across the Indian and Pacific Oceans but are not native to mainland Australia. Crab spiders, on the other hand, are small arachnids that never reach the massive size of a coconut crab.
Giant Coconut Crab Spider – Fact or Myth?
The phrase “giant coconut crab spider” is purely a myth. It merges two unrelated creatures: coconut crabs and giant huntsman spiders. This misunderstanding is fueled by viral internet images and exaggerated claims. In reality, no spider in Australia grows to the size of a coconut crab, which can weigh over 4 kg. Recognizing this distinction helps clear up one of the biggest misconceptions about Australian wildlife.
Australian Spider Crabs (The Crustacean)
General Overview of Spider Crabs in Australia
Spider crabs are marine crustaceans with long spindly legs and an orange to reddish shell. They are most commonly found in southern coastal waters, especially around Victoria and South Australia. Their alien-like appearance and massive gatherings during migration events make them a remarkable sight for divers and marine enthusiasts.
Size and Growth of Australian Spider Crabs
These crabs can grow quite large, with bodies reaching up to 16 cm in width and legs stretching over 70 cm. Their growth is closely linked to molting cycles, where they shed their hard shells to grow larger ones. During these times, they gather in massive groups for protection.
Are Australian Spider Crabs Edible?
Yes, spider crabs are technically edible. However, they are not widely harvested for food in Australia due to their limited meat yield compared to commercial crab species. Some recreational fishers collect them, but strict rules and seasonal restrictions apply. Their meat is sweet but requires effort to extract, making them less popular than mud crabs or blue swimmer crabs.
Giant Spider Crabs of Australia
The Giant Spider Crab Explained
The giant spider crab (Leptomithrax gaimardii) is one of the most impressive crustaceans in Australian waters. These crabs can weigh up to 10 kg and have incredibly long legs, making them appear even larger than their body size suggests. They are considered one of the largest crab species globally, rivaling the Japanese spider crab.
Giant Australian Crab Spider vs Giant Spider Crab
The terms “giant Australian crab spider” and “giant spider crab” are often confused. The former typically refers to large huntsman or crab spiders (arachnids), while the latter refers to actual crabs (crustaceans). The difference is straightforward: spiders belong to the arachnid family, with eight legs and no antennae, while spider crabs are marine animals with claws, gills, and hard shells.
Behavior and Habitat
Where Do Crab Spiders Live in Australia?
Crab spiders thrive in gardens, forests, grasslands, and even urban areas. They are most often spotted on flowers, leaves, or stems, waiting patiently for unsuspecting insects. Their sideways walk and crab-like posture help them stay hidden. Unlike web-spinning spiders, they rely on ambush hunting, striking quickly when prey comes close.
Spider Crab Migration in Australia
One of the most spectacular marine events in Australia is the annual spider crab migration in Port Phillip Bay, Victoria. Thousands of spider crabs gather in shallow waters as they prepare to molt. This mass congregation is believed to be a defense strategy against predators like rays and sharks. Divers and photographers from across the world travel to witness this unique phenomenon.
Regional Presence
Spider crabs are particularly common in South Australian waters and along the southern coastline. Meanwhile, crab spiders can be found across much of mainland Australia. Each region hosts slightly different species, adapted to local environments. Their presence highlights Australia’s biodiversity, both on land and in the sea.
Interaction with Humans
Are Crab Spiders Dangerous to Humans?
Crab spiders are generally harmless to humans. While they do possess venom to immobilize prey, it is not considered dangerous to people. Their bites are rare and may cause only mild irritation, swelling, or redness. In fact, many gardeners appreciate their presence since they naturally control insect pests.
Are Spider Crabs Harmless or Useful?
Spider crabs pose no danger to humans. They are slow-moving creatures that feed on algae, detritus, and small marine organisms. For divers, their mass migrations are a breathtaking experience rather than a threat. Ecologically, they help maintain balance in marine ecosystems by recycling nutrients and cleaning up the sea floor.
FAQs
1. Are Australian spider crabs edible?
Yes, they are edible, but not commonly eaten. Their meat is sweet yet limited compared to other crabs. Recreational fishing is possible under seasonal regulations, but they are not a major commercial seafood species in Australia.
2. How big can Australian crab spiders get?
Most crab spiders are small, only a few centimeters across. However, the term “giant crab spider” often refers to huntsman spiders, which can reach leg spans of 12–15 cm, making them appear much larger.
3. Do coconut crab spiders really exist in Australia?
No, there is no such species. The phrase mixes up crab spiders with coconut crabs, which are huge terrestrial crustaceans found on islands in the Pacific and Indian Oceans, but not on mainland Australia.
4. Where can I see the spider crab migration in Australia?
The best-known migration occurs in Port Phillip Bay, Victoria, usually during late autumn and winter. Thousands of spider crabs gather in shallow waters, creating a spectacular natural event for divers and photographers.
5. Can crab spiders in Australia bite humans?
Yes, but bites are extremely rare and not medically significant. Crab spiders are shy and prefer avoiding humans. If a bite occurs, it usually causes mild redness or swelling, with no lasting effects.
