While Homo sapiens are undeniably an incredible evolutionary wonder, capable of civilization and highly complex thought, there are several animals that also have amazing abilities that humans don’t. From super strength to limb regeneration, there is an impressive array of evolved abilities in the animal kingdom that are worthy of recognition and discussion.
In this two-part series, the abilities of the axolotl (Ambystoma mexicanum), the peacock mantis shrimp (Odontodactylus scyllarus), tardigrades (phylum Tardigrada), and the common cuttlefish (Sepia officinalis) will be discussed here in Part 1. In Part 2, the “immortal” sea jelly (Turritopsis dohrinii), the lyrebird (genus Menura), and sea cucumbers (class Holothuroidea) will be discussed.
The Axolotl
The axolotl (Ambystoma mexicanum) is a species of salamander that is paedomorphic, meaning that it does not undergo metamorphosis and instead, retains tadpole morphology (body form) into adulthood . Metamorphosis refers to when an animal undergoes a transformation from a juvenile physical form to the adult form. For example, caterpillars undergo metamorphosis to become butterflies.
Axolotls are a critically endangered species found in wetland and lake habitats of southern Mexico, and are named after the Aztec god of fire and lightning, Xolotl. These carnivorous amphibians feed on small animals such as worms, fish, and insect larvae and can live up to 15 years.
Axolotls have the remarkable ability to regenerate (regrow) parts of their body including limbs, eyes, and sections of the brain. While this ability is currently undergoing extensive research, there are a few reasons that have been proposed as to why and how these animals can do this. One possible trait that may allow for this regeneration of body parts is the fact that the axolotl stays in the tadpole stage and doesn’t metamorphosize into an adult form. Since it remains in a juvenile conformation throughout its life, it has been proposed that certain genes that are usually only active during the juvenile stage of an animal can to be activated in adulthood because the axolotl never underwent metamorphosis.
Studying the mechanisms of the axolotl limb generation is valuable because it can provide insights that can be applied to human medicine. In an article published by the National Library of Medicine, researchers were able to discover a link between the amount of nerves present at a regenerating limb and its size in axolotls. Findings like these contribute to a larger understanding of wound healing, and can contribute to new groundbreaking medical solutions to limb loss.
The Peacock Mantis Shrimp
The peacock mantis shrimp (Odontodactylus scyllarus) is one of about 480 species of crustaceans in the order Stomatopoda. Stomatopods are closely related to shrimp and lobster but are different due to unique use of their forelimbs and bulging eyes. They first appeared in the fossil record about four hundred million years ago, and they are most commonly found in tropical climates in shallow reefs. Mantis shrimp are territorial and solitary burrowers (U-shaped burrows) and are known to be quite aggressive hunters. On average, they live about three to six years but have been known to live up to 20 years.
The peacock mantis shrimp is the only (known) animal that can see circularly polarized light. This is a special type of light that allows them to visualize a very wide array of colors that humans cannot see. In total, they have sixteen photoreceptors that allow them to see visible light (what humans see) and UV light (like butterflies and bees). Photoreceptors are special cells in the eyes that are responsible for supplying color vision.
Mantis shrimp have compound eyes, which are the same type of eyes that are found in many insects and crustaceans. They are made up of several optical units called ommatidia. These ommatidia are what house photoreceptors.
Another incredible ability of the peacock mantis shrimp is its powerful punch. Mantis shrimp have raptorial club-shaped forelimbs, meaning that they have the ability to grasp things using barb or spear-like structures. These forelimbs resemble those of a praying mantis, which is how mantis shrimp got their name. Mantis shrimp are capable of fully extending these limbs at speeds of up to 2 milliseconds: this is equivalent to the acceleration of a 0.22 caliber bullet! The limb hits the prey with so much speed and force that the water surrounding the strike is vaporized (it turns to a gas) in what is known as a cavitation bubble. When these bubbles pop, light, sound and heat is emitted! It is considered to be one of — if not the most — powerful strikes in the animal kingdom. When kept in aquariums, they have been observed shattering the glass! Check out this video to learn more.
Here in California, we have a species of mantis shrimp called the California Mantis Shrimp (Hemisquilla californiensis), and they’re known for creating low rumbling sounds during territory defense or feeding. Check out this article to hear the sound and to learn a bit more!
Tardigrades
Tardigrades are a group of aquatic (that is, they require a layer of water on their body for gas exchange), microscopic (about 1mm long) invertebrates that consists of about 1300 species. They make up their own phylum, called Tardigrada (which means “slow stepper”) and first appeared in the fossil record about 600 million years ago. They have eight clawed limbs, and their plump body has given them the nickname “water bears”. Under normal conditions, the lifespan of a tardigrade is roughly around two months. However, certain survival strategies triggered by extreme environmental conditions can allow a tardigrade to survive for over one hundred years. They are found worldwide in a variety of habitats (deep sea, tropics, antarctica, high elevation) and feed on plant, animal and bacterial cells.
The tardigrades’ superpower lies in their unique ability to survive extreme conditions. Some of these conditions include hypoxic (lacking oxygen) environments, below freezing temperatures (as low as -328 degrees Fahrenheit), extreme heat (as high as 304 degrees Fahrenheit), exposure to X-ray radiation (one thousand times the human lethal amount) or toxic chemicals, boiling alcohol, and pressure extremes (low pressure from vacuum; six times the pressure of the deepest part of the ocean).
The way tardigrades can survive these crazy environmental settings is due to a special metabolic (chemically regulatory) process they undergo called cryptobiosis. Cryptobiosis refers to the death-like (yet reversible) state animals undergo, where their bodily processes cease. Other animals like rotifers, nematodes, and brine shrimp can do this, as well as other organisms like yeast and several plant species. There are different types of cryptobiosis, depending on the environmental condition the organism is reacting to. Most commonly, tardigrades undergo anhydrobiosis, which is a type of cryptobiosis triggered by the lack of water. When a tardigrade enters an anhydrobiotic state, it rolls up into a ball called a tun. When in this tun configuration, it metabolically synthesizes (makes within its body) a sugar called trehalose, which has the role of maintaining cells in the absence of water. When environmental conditions are once again favorable, tardigrades can emerge from their tun state in a matter of hours. To watch this process, watch this video!
An important distinction to know is that while tardigrades have the ability to survive extreme conditions, they are not considered to be extremophiles because they are not adapted to live in these conditions, they are only adapted to endure them.
Researchers at the Boothby Lab at the University of Wyoming are currently studying how tardigrades preserve themselves in such an effective way, and are looking at ways they can apply this process to the protection and preservation of human blood cells.
The Common Cuttlefish
The common cuttlefish is one of roughly 120 different species of cuttlefish. Cuttlefish are cephalopods (class) in the phylum Mollusca, so they are related to squid and octopuses but are in a different taxonomic order called Sepiida. A hallmark trait of cuttlefish is the cuttlebone, which is a chambered structure that plays a role in the animal’s buoyancy. The common cuttlefish is often called the European cuttlefish, because it resides in the eastern North Atlantic ocean, the English channel, and the Mediterranean sea. They inhabit shallow, sandy waters in the spring and summer, and migrate to deeper depths (100-200 m) in the winter and fall seasons. The common cuttlefish is roughly half a meter long, weighs around seven pounds, and has a lifespan of about two years.
Cuttlefish are known for their exceptional intelligence and stunning color-changing abilities. They have one of the largest brain-to-body size ratios out of all invertebrates, and have the ability to count and remember locations, contents, and times of their last meal. They also have the sensory capacity to detect certain visual cues (they’re colorblind, but have a large range of vision and can detect specific angles at which light reflects off objects) as well as olfactory (smell) cues. They can also detect “sound” cues in the form of pressure waves (pressure waves are differences in the amount of particles present in an area, creating rippling patterns of varied pressures). They are known to communicate with each other via color, specialized movements, and specific tentacle configurations. To learn more about the versatility of the behavior and color use in cuttlefish, check out this article by NatGeo that talks about a multitasking male cuttlefish!
Cuttlefish are able to change the color and texture of their skin, and do this for mating and hunting purposes. They are able to do this by possessing three special cells called chromatophores, iridophores, and leucophores; and by performing special muscular contractions near the skin. The eyes pick up the visual information needed for camouflage, and this information is taken to the brain, which is then delivered to the skin cells. The skin cells are attached to a network of muscles that contract in a certain way to produce the necessary pattern/color. To learn more about this mechanism, check out this video!
Be sure to check out Part 2 of the discussion of Amazing Animal Abilities, where the “immortal” sea jelly (Turritopsis dohrinii), the lyrebird (genus Menura), and sea cucumbers (class Holothuroidea) will be explored!
Sources
Axolotl:
Peacock Mantis Shrimp
https://academic.oup.com/jcb/article-abstract/37/1/109/3061623
https://www.boem.gov/newsroom/ocean-science-news/peacock-mantis-shrimp
https://ucmp.berkeley.edu/arthropoda/crustacea/malacostraca/eumalacostraca/stomatopoda.html
https://www.nationalgeographic.com/animals/invertebrates/facts/mantis-shrimp
https://www.akronzoo.org/invertebrates/peacock-mantis-shrimp
https://marinesanctuary.org/blog/sea-wonder-peacock-mantis-shrimp/
https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/compound-eye
Tardigrades
Cuttlefish
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