As we get to the end of the year, we enter a sticky situation as the worms return. And if you want to request an issue on an amazing animal, fabulous fungus, perplexing plant, or awesome paleofauna, don't hesitate to leave a request in the comments.
You may notice that this section is smaller than normal. That is because Onychophora is a relatively new clade designation, and its internal designations between Phylum and Family have yet to be determined.
Related Species: The Titicaca water frog is one of 63 species within the genus Telmatobius a group of frogs that are all found above 1000m above sea level in the Andes Mountain (1).
The velvet worm Euperipatoides rowelli, is a small blackish blue invertebrate that reaches a body length of up to 5cm, with fifteen pairs of legs. These legs are tipped with retractable claws and sensory pores, allowing them to detect chemical cues and vibrations in the environment around them. Movement consists of consecutive pairs of legs moving back and forth with the claws only deployed when climbing on hard surfaces. While Euperipatoides rowelli has eyes, they are very simple and only detect the difference between light and dark. As their name velvet worms suggests, Euperipatoides rowelli is covered with soft hydrophobic scales that given them a velvety texture (2), although it doesn't prevent the worm from desiccating, necessitating them to live in environments with high humidity. Because desiccation is an issue for Euperipatoides rowelli, it is primarily nocturnal and spend most of their time under logs and tree bark.
Euperipatoides rowelli is an obligate predator, feeding on a range of small invertebrates such as woodlice, bark lice and spiders among other species. Euperipatoides rowelli stalks up to its prey item, poking it with its antenna to determine the responsiveness of its prey and whether it commits to attacking. If the velvet worm decides to commit to the attack, it spray glue like slime from a pair of modified limbs on either side of the head, at a speed of 5m/s at an oscillation of 30-60 hertz (Hz) (3). The spray is aimed primarily at the prey's limbs, with the exception of spiders where the fangs are targeted, to immobilize the prey, before injecting digestive enzymes to commence digestion, while stabbing prey with enlarged fangs to dispatch it. Both the prey item and the dried slime are consumed, although Euperipatoides rowelli will abandon its meal upon sunrise.
Euperipatoides rowelli is a social species, living in groups of up to fifteen individuals, with a dominant female leading the group (4). This groups of velvet worms engage in cooperative hunting, with the dominant female feeding first, followed by lower ranking females, then the males and finally immature individuals, with disputes settled through biting, although this only is exhibited in mature animals. Mating is simple, with males depositing a packet of spermatophore onto her skin, with the sperm breaching through the skin barrier before swimming through the blood stream to her pair of uteri (5). Male and female Euperipatoides rowelli mature at different rates, with males reaching sexual maturity at the age of six months, with females taking three years to reach sexual maturity.
Ecology 101: A brief guide to Environmental Mechanics #32 - The long-awaited Taxonomy Talk
Taxonomy comes from the Greek words taxis (order) and nomia (method) and is the scientific classification and categorisation of living things. While the modern system of taxonomy that we use was composed in 1735, multiple attempts of categorisation had been attempted before then. One of the first major attempts was the Aristotelian system, who classified animals into two groups; the Anhaima (animals without blood) and Enhamia (animals with blood), with multiple groups within these categories such as 'those who lay eggs' or 'those who walk on four legs' among others (6). One of Aristotle's students, Theophrastus, expanded the system further by categorising almost 500 plants, some of which were adopted in our current taxonomic system, such as the genus Narcissus and Crocus among others.
It was Carolus Linnaeus, a Swedish botanist that outlined the modern framework of taxonomy in Systema Naturae in 1753. Linnaeus outlined the need for a standardized binomial identification for living things comprised of a genus and species, that is still used today (7). Additionally, Linnaeus set out the skeleton of our modern framework consisting of Class, Order, Genus and Species, with additional higher categories and subcategories added as knowledge advanced. With the advancement of genetic sampling, 'taxonomic shakeups' particular on the family level and lower, have reshaped the relationship between living things, but generally has kept the higher branches intact, providing pathways detailing the ancestral lineage species through taxonomic ranks.
Once in a clade, a species is included within all the clades above it. For example, the gemsbok (Oryx gazella) is not only part of the genus Oryx which contains three other species, but also a bovid (cattle, goats, antelope), an artiodactyl (a groups that contains camels, pigs, whales and giraffes among others), a mammal (an animal that has mammary glands), a synapsid, an amniote, tetrapod, vertebrate, chordate and animal. If a population of gemsboks were to evolve into another animal, it would remain in all these groups, no matter how far a species evolved it can't escape the cladistic boxes that defines the path that led to its current form.
While Linnaean taxonomy sets up a framework for classification, it is largely immobile and does not deal with paleo-taxa very well. A new identification system known as cladistics was used to categorise birds in 1901, and later insects in 1921, with the term clade introduced in 1958 by Julian Huxley (8). Cladistics are the modern way to determine ancestry and relationships between living things, to create cladograms that have multiple branches relating to living things. Cladograms are mutable with new developments in genetics, for example new genetic evidence has showed that turtles are more genetically similar to crocodiles, non-avian dinosaurs and birds than lizards are (9), when lizards previously were classified as closer to the archosaurs.
When determining what clades animals were members of, Linnaeus looked at multiple physiological features to determine relationship. For example, Linnaeus concluded that whales despite having similarities to fish (not to mention the previous assumption that all things living in water were fish), were in fact mammals due to their respiratory and reproductive traits, in part due to his student Pehr Lofling's work on the boto (10), by the time the 10 edition of Systema naturae was released. Whales are a good example of the ever-evolving field of cladistics, between gene sequencing, study of anatomy (most notably the ankle joint and the stomach morphology) and the discover of fossil taxa, we now know whales are artiodactyls. This discovery is so recent that the earliest issues of Impurest's Guide to Animals regarding the vaquita (Phocena sinus) published in 2014 still uses the old taxonomic name for whales Cetartiodactyla (11).
Modern gene sequencing has been the main driving force for the discovery of new species. Just this year, the green anaconda's (Eunectes murinus) genome revealed that this species was two species, with the northern green anaconda (Eunectes akayima) being a separate species (12). While the discovery of new species through genetic profiling, the split in species can cause species to decline in population. For example, the splitting of the common skate into two species; the blue skate (Dipturus batis) and the flapper skate (Dipturus intermedius) in 2009, leading to both species to be classified as 'Critically Endangered' by the International Union for Conservation of Nature (IUCN).
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Next week we our penultimate issue as we mussel in one last animal before the seasonal special. And if you want to see more amazing animals and plants, please check out the Oddity Arkive or past issues. And if you want even more animals, please check out the dearly departed Impurest Cheese's Guide to Animals, which can be found here or on the blog of the walking Paste-Pot-Pete impersonator @ficopedia.
If you still have a yearning for learning, please check out the master list of Mr Monster's Martial Arts Journey.