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Which Animals Can Regrow Body Parts?

Mediterranean Gecko shortly after dropping its tail to avoid a predator
Matt Jeppson/Shutterstock

Regeneration isn’t found among many species of animals, but some can lose body parts and grow them right back. These abilities differ for different critters, and some of them are helping science in a big way.

Lizards

Lizards are one of the most common animals you hear of growing back body parts. Lizards can drop their tails when they feel threatened. The lost tail keeps wiggling to distract the predator while the lizard gets to safety.

The problem with losing a body part, even for protection, is that the regenerative process takes time. It can take months for a lizard to grow back its tail. However, lizards are one of the animals being studied by scientists to help learn about the process of wound healing and genetics.

Salamanders

The miraculous immune system of all sorts of salamanders may be the reason why these critters are not only able to grow back lost limbs but are also able to regenerate portions of damaged vital organs.

Scientists have been watching the axolotl, a water salamander, to learn about tissue regeneration in humans. Macrophages, immune cells in the salamanders, are required for limb growth. The fewer the salamander has, the longer regeneration takes.

Flatworms

Even more impressive than a salamander’s immune system is the flatworm’s ability to be cut in half and grow back as two worms. The tail part of the worm will produce a new head, and the head part will develop a new tail.

Of course, not all flatworms have this ability. Some worms can only partially regenerate, and other species can’t regenerate at all. Some genes need to be in play for the worms to grow back their parts, and this is what science has been looking into.

Sea cucumbers

Named for their cucumber-like appearance, the sea cucumber is another worm-like critter that can regenerate when it’s cut in half, but that’s not the coolest (or grossest) ability it has.

What’s even more remarkable than growing back a limb or tail is the sea cucumber’s strange defense mechanism. To frighten away predators, the sea cucumber pukes up its intestines (leaving something else for the predator to eat than them, possibly), and then grow them back within a couple of weeks.

Sea Urchins

Much underwater wildlife can regenerate body parts. Sea urchins, with their spiny body, are already unique in appearance. These echinoderms look like spike-covered blobs on the ocean floor and in saltwater fish tanks. They sometimes lose their spikes. Lucky for the sea urchins, they’re able to grow back the spines they lose. The spines are hard, made from calcium carbonate.

You can find broken off spines on saltwater beaches and in gift shops. You no longer have to fret, though, since it only takes a few days for the sea urchin to regenerate those lost spines.

Sponges 

Another strange underwater creature with regenerative abilities is the sponge. There are many different types of sponge animals living in the oceans. They look like plants, but they are an animal species.

Sponges can regenerate lost parts, which is near. But, even neater is the ability of one section of a sponge to regenerate into another adult sponge. On top of that, if a sponge comes apart, it can later reattach to it’s missing parts.

Starfish 

Starfish can lease a limb and grow a new one back. Essentially, the process of regeneration works for starfish much the same as when they grow in the embryonic stage. Starfish may use their stem cells to help with this regeneration (something that has been going through human studies as well).

Limbs aren’t the only things that starfish seem to have the ability to regenerate. There was a starfish in an aquarium in the UK that lost a limb, and the limb started growing a new body!

Octopus and Squids

Cephalopods have the same ability as starfish to grow back a severed arm, but they don’t have all of the fantastic regenerative capabilities of the starfish. A severed octopus or squid arm will never grow back another animal. The limbs simply die when they’re no longer attached to the animal.

The cephalopod’s new limb is just as good as the original, suckers, and all.

Deer

More land animals have regenerative abilities, although there may be fewer on land than in the water. One type of animal that “practices” regeneration regularly is deer. Deer shed their antlers every single year, and grow back new ones.

Deer antlers are built of calcium and phosphorus, and grow back easily when it’s time for regeneration. Each time deer grow back a new set of antlers, they come in larger. All species of deer shed their antlers in the winter and begin regrowth in the spring.

Spiders 

If you see a spider with fewer than eight legs, it’s still a spider; it just dropped a couple of limbs. Unfortunately, the loss of limbs impedes the spider’s ability to get food and can cause other problems for them.

While spiders can lose legs in accidents, they sometimes drop their legs (on purpose) as a defense strategy. It could be for the same reasons sea cucumbers expel their intestines, and lizards drop their tails as a way to distract something coming after them.

Yvonne Glasgow Yvonne Glasgow
Yvonne Glasgow has been a professional writer for almost two decades. Yvonne has worked for nutritionists, start-ups, dating companies, SEO firms, newspapers, board game companies, and much more as a writer and editor. She's also a published poet and a short story writer. Read Full Bio »