Last Sunday, rabbits around the world went on their annual egg-laying extravaganza. Every year, on Easter Sunday, these normally unassuming mammals defy the laws of nature and switch from having live bunny babies to laying colorful chicken eggs. Some people have even spotted them taking this bizarre tradition one step farther and clucking like a chicken while laying chocolate eggs. Of course, no rabbit except the Easter Bunny is truly capable of this fantastic feat, but there are some unusual mammals who can, in fact, lay eggs. The eggs may not be chocolate or neon-colored, but the animals that lay them are remarkable nonetheless. This strange group of mammals, called monotremes, consists only of one species of platypus and two species of echidna.

Echidnas, or spiny anteaters, seem to be a strange cross between a hedgehog and a koala. Once a year, these animals lay one tiny egg less than two centimeters long into a pouch on their stomach. Ten days later, young echidnas hatch out blind and hairless. They stay in the pouch for 12 weeks, though they grow spines when they are 8 weeks old. When in danger, an echidna has two options: It can either roll into a ball or quickly burrow into the dirt and create a protective mound on either side of its body. Either way the spines that give the spiny anteater its name are its greatest defense, providing an intimidating prickly barrier between it and any potential predators.

Platypuses are even more interesting in many ways. One of the most identifying features, the flattened "duck bill," is actually an advanced hunting tool. The underside of the bill is lined with electroreceptors that can sense the electrical signals given off by an animal's muscle contractions. By sensing the strength of these signals across the surface of its bill, the platypus can accurately pinpoint and capture its prey. Other animals such as sharks and rays can do this, but there are no other known mammals with electroreceptors.

Another highly unusual characteristic of the platypus is the presence of a venomous spur. Male platypuses have spurs on their hind feet that are used to fight other males during the mating season. The venom in these spurs causes localized paralysis, swelling and extreme pain that can last for several months. It has never been linked to human death but can kill smaller animals, including cats and dogs.

Though a monotreme may be a more authentic candidate for an Easter egg layer, just imagine how much harder the eggs would be to find. I suppose a venomous animal may not be the best replacement for the Easter Bunny anyway. Maybe next year the Easter Bunny will be nice enough to hide some monotreme eggs along with its own. I have a feeling they will look a lot like jelly beans.

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