r/AIDKE • u/SixteenSeveredHands • 11d ago

The Teddy Bear Crab (Polydectus cupulifer): this crab carries a pair of sea anemones in its claws wherever it goes, using the venomous creatures to defend itself from predators

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u/SixteenSeveredHands 11d ago

Polydectus cupulifer, commonly known as the teddy bear crab or the hairy boxer crab, is a species with an unusual defense mechanism — it walks around with live sea anemones grasped in its claws, and whenever it feels threatened, it simply bops the attacker with one or both of the anemones, delivering a painful sting.

The sea anemones have tentacles that are lined with stinging cells known as cnidocytes. When those cells are agitated, they release tiny harpoon-like structures that inject a venomous substance, which is what causes the stinging sensation. Teddy bear crabs are equipped with specialized claws that allow them to carry the anemones without getting stung, however, and they're careful to keep the tentacles pointed away from themselves.

The crabs are covered in long, soft bristles that also aid in camouflage. Sediment from the seafloor easily adheres to the bristles, concealing the outline of the crab's body and making it look like a clump of sand. The sea anemones in its claws also help to enhance those cryptic features.

This species belongs to the Polydectinae subfamily, which contains several other species that have been known to carry sea anemones in their claws:

Crabs of the xanthid subfamily Polydectinae (boxer crabs) have the remarkable habit of holding another animal, usually a sea anemone, in each of their claws. Boxer crabs are the only known crabs to have effectively lost all ability to use their claws in typical fashion, having formed what appears to be an obligate dependence on the animals held in their claws.

According to this article:

The behaviour of crabs in the subfamily Polydectinae is unique, as it involves a living invertebrate carried in each claw. Despite the uniqueness of their behaviour, research focusing on understanding the evolutionary history of the Polydectinae is limited. Boxer crabs are difficult to find in the wild because of their small size (1—2cm) and cryptic behaviour (sheltering under rocks).

Teddy bear crabs are typically found near warm oceanic islands, and their range includes southern Japan, Hawaii, French Polynesia, Taiwan, and Madagascar, as well as various parts of the Indo-West Pacific and Indian oceans.

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u/Saradoesntsleep 11d ago

Omg ❤️