If the earthworm became pink and grew legs, would it be cute?

This pink creature in the picture looks very strange - it has a lizard head, a snake body, and mole claws, and its soft appearance makes it look like an earthworm.

Tadpole asked a sincere question online: What kind of creature do you think this is?

Do many of you think it is the soil scavenger - earthworms?

In fact, this is a type of animal called caecilians, also known as worm lizards, with the scientific name Amphisbaenia. It is mainly distributed in Africa and South America, and a small part is distributed in West Asia, the Iberian Peninsula, Central America, the Caribbean, the Florida Peninsula, the Baja California Peninsula and central Mexico.

There are six main families of caecilians: Amphisbaenidae, Trogonophidae, Bipedidae, Rhineuridae, Cadeidae, and Blanidae. The caecilians in the photo above belong to the five-toed bipedal caecilians (Bipes biporus), which are extremely unusual because they have forelimbs. However, other caecilians without forelimbs also have remnants of limbs as evidence of their existence.

When people first see caecilians, they are often easily mistaken for earthworms, but they are not closely related to earthworms.

01

Not related to earthworms, but related to lizards

Both the caecilians and earthworms have the character “虫” in their names, but perhaps their only connection is their easily misidentifiable appearance.

From the perspective of body structure, earthworms are annelids, without bones or legs, while caecilians are proper vertebrates. They have bones, scales, and five-toed bipedal caecilians have a pair of stubby forelimbs.

In terms of reproduction, when the eggs of earthworms mature, they will form cocoons outside the annulus. After the eggs are fertilized in the cocoons, the cocoons leave the earthworms and remain in the soil with both ends closed. Most worm lizards are oviparous, but some worm lizards are viviparous. Oviparous worm lizards lay their eggs in ant nests, where they are incubated by the temperature of the ant nests.

In terms of feeding habits, earthworms are omnivorous animals, mainly eating humus and bacterial decomposition products. Calyx lizards are carnivorous animals, mainly feeding on the larvae of large beetles and some other insects.

Why are caecilians and lizards considered relatives when they look nothing alike? This story begins with a lizard fossil found in the Messel fossil deposits in Germany that dates back about 45 million years. German paleontologist Johannes Muller named the fossil "Cryptolacerta hassiaca," which means "lizard hidden in the Hassia."

Under the CT scanner, this fossil has the same thick skull features as modern caecilians, and some structures are extremely similar to caecilians, such as small eye sockets and thickened bones. In addition, genetic analysis has also concluded that caecilians are most closely related to lizards. This is enough to show that the relationship between caecilians and lizards is real.

Although they are relatives, most caecilians do not have the ability to break their tails that lizards have. Even if a small number of caecilians can break their tails to escape when their lives are at stake like lizards, this kind of tail breaking is a one-time thing - if the tail is broken once, it cannot be regenerated the second time it is broken.

The regenerated tail of a lizard after its tail is broken off does not have segmented caudal vertebrae, but is just a continuous tubular "cartilage", and the arrangement and structure of the scales are also different from the original tail. Naturally, the regenerated tail of a caecilian lizard after its tail is broken off is also different from the original tail.

02

Do caecilians crawl like earthworms?

The caecilians use their necks and protruding mouths as fulcrums to crawl forward. As they crawl, their bodies bend, straighten, and bend again, over and over again, just like an accordion being played.

When a caecilians crawl, it looks like the skin on the surface is driving the entire body forward, but this is not the case. This is because the skin on the surface of the caecilians is loose, so some ring-shaped body segments will appear when crawling, which is somewhat similar to a crawling earthworm.

However, despite their appearance, the crawling methods of caecilians and earthworms are essentially different. When earthworms crawl, they move forward segment by segment through the alternating contraction of their muscles and the coordination of their body bristles. However, caecilians have no body bristles and mainly rely on the fulcrum strength of their necks and snouts. Caecilians with forelimbs will also use their forelimbs as an aid.

03

A cute appearance hides a fierce nature

Although the caecilians do not look lethal, they are very ferocious by nature. They have powerful mouths, and when they hunt, they use their upper and lower teeth to tear the prey into pieces and then swallow them.

When threatened, the caecilians will retract their tails into their bodies, making it difficult for predators to distinguish between their head and tail. When the predators grab their tails, the caecilians will turn their heads around and bite the predators hard, thus counterattacking the predator.

It is the unique feature of the caecilians that their tails can be retracted that makes it easy for the tails to be mistaken for heads. Therefore, the caecilians' scientific name comes from the two-headed snake Amphiboebiscus in ancient Greek mythology. This legend adds a lot of mystery to the caecilians.

If you encounter a caecilians while traveling in South America in the future, congratulations! This kind of animal lives underground for a long time and only comes to the surface to keep warm. It is very lucky to meet this creature on the surface!

But don't think it's a big pink earthworm!

END

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