Table of Contents
Primitive Animals Definition
Incorrect taxonomic classifications classified creatures as either animals or plants, respectively, in the Plantae and Animalia kingdoms. This would turn out to be inaccurate, as certain creatures fall into both groups, rendering the previous taxonomic categorization ambiguous. However, eukaryote animalia creatures were assumed to be wandering the oceans throughout the Cambrian Era, after diversifying further via natural selection and mutation from the earliest multicellular organisms.
Around half a billion years ago, these animals would have arrived on the planet via evolution, gradually diversifying from their parents into new separate species occupying their unique biological environment. Because life was diversifying at a faster rate in the great scheme of things, taxonomists used increasingly accurate classifications across the geological ages.
The appearance of different multicellular creatures has led to the classification of these species into Phyla. It’s worth noting that the mineral makeup of modern creatures, such as humans, is comparable to that of these ancient species that evolved from the water. As a result, we may conclude that animals, as well as life in general, evolved from the water. In each respective phylum (sub-taxon of kingdoms) mentioned below, this period of time resulted in a plethora of genetic variety.
Primitive Animals and Worms
Worms were among the earliest creatures to diversify on the planet. In the watery environment, their flattened shape would have aided them in moving against currents. Remember that mobility was a major value for creatures at the time, thus this provided a significant selection advantage through time.
Because worms have been present from the beginning of time in terms of life, their genome has evolved to suit a wide range of biological niches and habitats, to the point that many species of worm are parasitic in nature. The Phylum Taxon categorization examines worm species in further detail, with each split into its own Phylum:
- Platyhelminthes is the phylum that includes flattened and worm-like animals.
- Nematoda is the phylum that includes roundworms.
- Annelida is a phylum that includes segmented worms.
Primitive Animals and Molluscs
Molluscs, such as snails, slugs, and mussels, are distinguished from other creatures by features such as the presence of feet, a tongue, an exoskeleton, and/or gills. One or more of these traits would be present in this categorization of creatures.
Molluscs, of course, have distinct traits and hence selection advantages in and of themselves. The capacity of their feet to claw their way through the ocean and sea floors, for example, meant that the bottom could be scoured more carefully and effectively, and mobility would have been easier.
Primitive Animals and Coelenterates
Although these creatures are old in origin, they now comprise the Great Barrier Reef off the coast of Australia, which is the world’s biggest single living structure. These creatures developed to acquire a variety of offensive traits, earning them their own taxon. Jellyfish, corals, and sea anemones are examples.
Coelenterates have a variety of features, including but not limited to;
- Tentacles that may sting prospective dangers as well as their prey with neurotoxins.
- It has a jelly-like look.
- A change in the generations.
These species can generate asexual offspring one generation and sexual offspring the next (perhaps suggesting the transition of sex, natural selection favouring one way or the other over time).
Primitive Animals and Echinoderms
Echinoderms, like all other animals evolving during the Cambrian epoch, were basic creatures. Their five-part symmetry was an intriguing feature, as the number five is a typical number associated with projecting bodily parts (i.e. fingers and toes). This grouping of creatures is exemplified by the term “starfish.”
It has lasted from the Cambrian Era until the present day, half a billion years later. Some have speculated that they may have a common ancestor many, many years ago based on their features, but owing to the timeframes involved, there is inconclusive evidence. The starfish’s 5-star shape allows them to pry open clams, sometimes in unison for nourishment. These are all instances of life’s ongoing development.
These creatures were the first of many, and they have continued to diversify in their quest for survival. The battle for the right to survive was heating up, and organisms continued to progress in a complex manner as a result of competition.