The caecilian is one of the weirdest species in the world. It looks like a worm or a snake, but this creature is an amphibian like a frog or a toad. You barely see it because it lives a quiet life in the burrow underground. Here are some surprising facts about caecilians!
Phylum: Chordata
Class: Amphibia
Order: Gymnophiona
1. They are the most unusual amphibian species
The caecilian is a very rare type of amphibian. They don’t have limbs, but a long body that can range from 3 – 5 feet (91 – 150 cm). This feature makes people easily mistake them for snakes or earthworms. They can have short tails or not.
Their skin is smooth and slippery. It is composed of multiple annuli, which are ring-like folds. These make the animals look segmented. Except for Scolecomorphidae and Typhlonectidae species, their skin hides dermal scales.
Caecilians, unlike earthworms, have large nostrils and a mouth that is full of needle-like teeth in each jaw. The majority of them have lungs, but they can also breathe by absorbing oxygen through their skin.
Their eyes are tiny and covered by a skin layer. This is because they don’t need to use their vision much when living in the burrows. Most people think that these species can’t see, but they are not. They still can distinguish between nights and days.
Another unusual thing about the species is that they have a pair of tentacles. Locating between their nostrils and eyes, these small sensory tentacles help them analyze their surroundings and find prey. They are the only amphibians with this characteristic.
The hue of the amphibian varies depending on where it dwells. They range in color from gray and black to dazzling blue, purple, emerald, orange, and yellow. Some species have 2 colors; some, like a coral snake, have dozens of vertical lines.
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2. Habitat
Caecilians live throughout the world, from tropical and subtropical wetlands to terrestrial locations. They are found in Central and South America, as well as Central Africa and from South to Southeast Asia.
Like other amphibians, they can dwell in both land and water. The majority of species spend most of their life underground or staying in shallow rivers.
Gymnophiona derives from the Greek terms gymnos and ophis, which mean “naked” and “snake,” respectively. However, these amphibian species are either not snakes or blind.
3. There’re about 200 caecilian species
The caecilian has 10 distinct families and roughly 200 distinct species. They are the only amphibians that have such a wide range of species.
Their 10 families include Scolecomorphidae, Ichthyophiidae, Caeciliidae, Herpelidae, Siphonopidae, Dermophiidae, Rhinatrematidae, Chikilidae, Indotyphlidae, and Typhlonectidae.
Some of their notable species are:
– Caecilia thompsoni is the biggest, measuring about 5 feet (2.4 meters) and weighing up to 2.2 pounds (1 kg).
– In contrast, Idiocranium russell is the smallest, having a size of only 3.5 inches (90 millimeters) in length. Due to its small size, it’s usually mistaken for worms
– Atretochoana eiselti and Caecilita iwokramae have no lungs. They breathe through the skin.
– The dead ringed caecilian (Siphonops annulatus) looks like a snake and might inject venomous when biting.
– The Sagalla caecilian (Boulengerula niedeni) live only in a tiny area on Kenya’s remote Sagalla Hill.
– The Aquatic caecilian (Typhlonectidae), also known as rubber eels, lives underwater.
4. Behavior
Besides the weird appearance, these species also have unusual behaviors.
Of 200 caecilians species, most of them live a lonely life underground. They spend most of their lives there, digging, hunting, and reproducing. However, the giant caecilia pachynema species from Ecuador still emerges to the surface in rainstorms and at nighttime.
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To live in the ground, the species have all adaptions they need. Thanks to their tough skull, pointed snouts, and two sets of jaw-closing muscles; they can effortlessly make their way through dirt or sludge.
In the burrows underground, they move by pushing their heads forward and drawing the rest of their bodies through behind them. On land, they move like worms, but in the water, they move like eels. Some species can even hold their breath for 30 minutes underwater.
5. They consume their prey whole
These species eat various foods. Their diet could include crickets, mollusks, larvae, beetle pupae, earthworms, small fish and snakes, frogs, termites, lizards, and even other caecilians.
Not all caecilians have the same diet. As they live in different habitats and have varying sizes, they eat different food. Terrestrial caecilians eat tiny insects and earthworms, whereas aquatic species consume small fish and invertebrates.
To locate the prey, these worm-like creatures use their excellent sense of smell and taste to identify the chemical signals of the prey. Then they grab the prey with their keen needle-like teeth. After that, they just swallow the entire prey, like pythons. They can also make their prey paralyze with the venom through their bite and bring them back to their burrow to eat later.
Snakes, fish, birds, pigs, and tenrecs are among the amphibians’ predators. To ward off predators, the species secrete toxins from skin glands.
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6. Females feed babies their body parts
To breed, they only use internal insemination. The male will use his long, tube-like phallodeum to mate with the female. The process lasts for about 2 – 3 hours, then the pair separates.
Like salamanders, these worm-like creatures can give birth and lay eggs. Approximately 25% of them are oviparous (lay eggs), while the remaining 75% are viviparous (give birth to offspring).
Their eggs are laid in a batch close to shallow water or moist ground. The mother protects her eggs until they are hatched. The eggs will be hatched as larvae or as fully metamorphosed young. This’s up to the species.
The young of both oviparous and viviparous species will be with their mom for 4 – 6 weeks.
One of the most interesting things about caecilian reproduction is the way the mother feed their babies. The mother will feed them her own body parts.
– With the newly hatched
The skin layers of the mother will become thicker and contain more fat and protein. These skin layers will be fed to her young. The young at this time have a specific set of temporary fangs which are used to scrape and remove their mother’s epidermis from her body without hurting her.
This strange behavior only exists in this species and it is called dermatotrophy.
– With the newborn
In viviparous species, the young starts eating on their mother before birth by nibbling away at the bulging covering of her oviduct. Scientists called it matriphagy. This action causes no harm or discomfort to the mother.
A female can lay a cluster of 30 – 60 eggs or give birth to 2 to 25 young. Juveniles have only a long, dark, thin stripe on their backs and are unpigmented.
In captivity, caecilians’ lifespan can last for 13 years. But in the wild, it’s still unknown how long they can live.
7. Conservation status
Many caecilians are threatened by habitat loss. In some locations, people mistake them for snakes and kill them right away.
Among 200 species, most of them are currently classified as Least Concern or Data Deficient by the IUCN. However, 13 of them are recognized as being in decline, 3 of them are categorized as Near Threatened, 4 as Vulnerable, and 10 as Endangered.
The Mount Oku Caecilian (Crotaphatrema lamottei) from Cameroon is the only species listed as Critically Endangered.
References:
- Caecilian – https://a-z-animals.com/animals/caecilian/
- Caecilians – https://www.nationalgeographic.com/animals/amphibians/facts/caecilians
