8 Must-Know Facts About Caecilians


Facts About Caecilians
13 Jun, 2024

Caecilians, which resemble worms or slick snakes, are lesser-known limbless amphibians that inhabit beneath the earth’s surface. There are nearly 200 species, varying in size from less than three inches to nearly five feet. 

Do you want to learn more about these small, creepy creatures? This comprehensive guide provides some amazing facts about caecilians.

8 Must-Know Facts About Caecilians

1: Their Name Originates From the Latin Word “Caecus,” Which Means Blind

The name “caecilian” is derived from the Latin word “caecus,” meaning “sightless” or “blind,” reflecting their often reduced or hidden eyes. The name comes from the taxonomic name of the first species, Caecilia tentaculata, which was discovered by Carl Linnaeus. Furthermore, Wilkinson et al. (2011) categorized the caecilians into nine families and 200 species.   

2: Caecilians Are the Sole Amphibians That Have Tentacles

Caecilians stand out among amphibians for possessing retractable tentacles, which function as sensory organs. Positioned between the nostrils and the eyes, these specialized tentacles aid caecilians in locating prey by conveying chemical cues from the environment to their nasal cavity (serving as olfactory organs). This adaptation is particularly vital due to their underground lifestyle, which restricts their dependence on vision.

3: They Possess Highly Muscular Jaws

Caecilians boast highly muscular jaws, which are enriched with two distinct sets-closing muscular muscles on either side of the jaw joint. These muscles are functionally separate: 

  • The jaw adductor muscles have parallel fibers and are positioned close to the jaw joint. 
  • The hypaxial interhyoideus posterior (IHP) muscles help close the jaws by exerting force on the retro-articular process (RA) of the lower jaw. 

These highly muscular jaws and their lever mechanics make caecilians well-suited for rapidly closing the jaws, thus enabling them to have a strong and efficient bite. 

4: Some Caecilians Have No Eyes at All, Others Have Tiny Eyes That Are Covered in Skin

Yes, it’s one of the most common unknown facts about caecilians that some have extremely small eyes, while others lack eyes altogether. In certain species, the eyes are completely covered by skin, facilitating adaptation to their predominantly underground existence.  

The tiny eyes are not for visibility; they can only sense light and dark. Due to their impaired vision, caecilians rely heavily on their acute sense of smell to forage for prey.

5: Two of Every Five Amphibians Face the Risk of Extinction

According to the second Global Amphibian Assessment, habitat loss, climate change, and disease are the primary threats to frogs, salamanders, and caecilians, with two out of every five amphibians facing the risk of extinction. 

This international research evaluated the extinction risk of over 8,000 amphibian species worldwide, including 2,286 species, for the first time. The results underscore the pressing need for conservation initiatives aimed at mitigating these significant threats and safeguarding amphibian biodiversity.

6: Their Size Varies by Species, Ranging From 3 Inches to Over 5 Feet

Caecilians, legless amphibians, exhibit a notable size range spanning from 3 inches to 5 feet, varying across species. The smallest among them, such as Idiocranium russeli from Cameroon, measures approximately 3.5 inches in length. In contrast, the largest species, like Caecilia thompsoni from Colombia, can reach nearly 5 feet in length. 

With nearly 200 documented species, caecilians display a remarkable diversity in size, from tiny, worm-like forms to those as long as some snakes.

7: The Heads of Caecilians Are Specialized for Burrowing

Caecilians are amphibians that live predominantly underground, burrowing through soft dirt. Their heads are specially adapted for this lifestyle, featuring hard, thick, and pointed skulls that help in efficient digging. 

Due to their subterranean habitat, caecilians have limited reliance on vision or hearing, resulting in underdeveloped sensory capabilities in these areas. However, their specialized skull structure enables them to navigate and thrive within their tunnel networks with remarkable efficiency.

8: Caecilians Are Powerful Crawlers

Caecilians are powerful crawlers despite being little-known among vertebrates. Mostly hidden in muddy burrows, these creatures rarely appear on the surface. Their strong, muscular bodies allow them to crawl through dense, compact soil efficiently. 


Caecilians may be lesser-known amphibians, but they captivate with their unique adaptations and behaviors. From their blind origins and specialized tentacles to their muscular jaws and varied sizes, caecilians display a huge array of characteristics. 

The above-discussed caecilian facts offer a glimpse into the intriguing world of these incredible creatures, enriching your understanding of their unique biology and behavior.


What is unique about caecilians?

Caecilians are unique among amphibians because they are limbless and possess retractable tentacles that serve as sensory organs. These tentacles help them detect chemical cues in their environment, which is crucial for their subterranean lifestyle.

Do caecilians have jaws?

Yes, caecilians have highly muscular jaws with two distinct sets of jaw-closing muscles, enabling them to have a strong and efficient bite.

How long do caecilians live?

Aquatic caecilians have a lifespan of 4 to 5 years in the wild. However, they tend to live longer under human care.

Are caecilians poisonous?

Yes, caecilians are poisonous. These may be the first known amphibians to possess venom glands in their mouth.

Are caecilians blind?

Caecilians are not entirely blind, but they have very small eyes that are often covered by skin, limiting their vision to only sensing light and dark. Some species have no visible eyes at all.

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