4 Things About Axolotls

4 Things About Axolotls

Vacuums?

In water, axolotls are a bottom band feeder, usually with a downward facing/'inferior' mouth but can be upturned too. It is tubular-shaped and opens into a complete chasm, augmented when combined with swimming for area coverage using suction. The suction adaptation seems to explain the goofy smiles - particularly when swallowing.

For easier swallowing/digestion, they can use substrates like gravel to grind up food instead of teeth, despite having tiny vestigial ones. Too much could cause a blockage - resulting in 'mouth pumping'. They may not use their teeth, yet they can still rip other axolotls' limbs or tails - mainly if hungry or agitated. Even so...

Regeneration

Regeneration is the axolotl's most infamous feature, consistently regenerating every tissue perfectly without permanent scarring. Although there is an apparent limit for the same limb - around the fifth time, scar tissue will form - preventing further regeneration. On the other hand, sometimes axolotls can regrow a damaged limb alongside an additional one, where they can effortlessly accept transplants from other individuals.

Some other healing examples include the tail, spinal cord, spine, jaw, eyes and internal organ tissues such as the heart and parts of the brain. The procedure takes at least a few weeks, likelier over months - taking longer with greater damage extent.

Mitosis cell division occurs after a wound is covered first with epithelium. It involves a new blastema (masses of stem cells) capable of growth and increasing differentiation. They eventually become more specified towards a particular function, forming various structures constituting organ/body parts like muscles or bones.

For example, concerning a limb: wound epithelium envelops the severed edge -> becomes innervated (e.g. sensory/motor fibres) -> blastema tissue -> cell accumulation -> differentiation -> regeneration.

Neoteny

Caused by a homozygous recessive allele pairing - axolotls are paedomorphic, differing from the typical amphibian metamorphosis, technically being adult tadpoles. They naturally retain larval stage attributes throughout adulthood whilst still being capable of reproduction. Rudimentary lungs and legs develop for any needed terrestrial navigation, where the gills also commonly get kept, unlike most salamanders.

Otherwise, the gills become absorbed into the body if, for some reason, they move out of deep water or live in shallower water. Most amphibians are born in water and then live on land as adults, however; axolotls are more aquatic and can basically stay submerged for their whole lives.

Neoteny aids survival by requiring lower nutrition quality/quantity due to having less mass for energy conservation in harsher environments like aquatic lakes on mountains with food scarcity. Whereas axolotls still undergo more implicit metamorphosis - involving internal physiological modifications such as haemoglobin shape changes to hold more oxygen.

They don't produce the needed thyroid-stimulating hormone (hypothyroidism) for metamorphosis, except it can get artificially invoked if externally administered. It involves higher concentrations of iodine or thyroxine, which is unnatural and can be fatal.

The expected terrestrial adaptations are the appearance of eyelids to blink for moistening and protecting against dust/dirt, lung development, fin plus gill absorption, decreased skin permeability to water for hydration maintenance on land - and lastly, muscular enhancement to cope with the lack of buoyancy.

Gills

As expected for salamander larvae, axolotls have external gills, where increased surface area helps with gas exchange. They look similar to feathers on the protruding stalks that extend out to the sides from the back of the head.

They flap the gills to swirl the surrounding water, promoting oxygen uptake - which is most useful regarding stagnant water with low oxygenation. In captivity, the water quality and flow should be adequate enough (with filters and bubblers e.t.c.) to avoid excessive flapping, rapid gulping or regular surfacing to breathe more. They are still partially skin breathers as amphibians - so filthy water is disrupting and irritating.

Axolotls can also use them for displays of dominance (as they are primarily solitary), as a sudden hunting mechanism to startle/overwhelm prey and even kick/scratch them with the hindlimbs like a dog.