Invertebrates are animal genus that lack or do not build up a spinal column. They account for the largest percent of all the living species. The first animals to have evolved were invertebrates. Data from fossils collection shows that invertebrates were there 600 million years ago. Some paleontologists propose that invertebrate animals emerged much earlier probably one billion years ago. Trace fossils such as burrows and tracks established in the Tonian age signify the presence of triploblastic worms approximately as large and complex as earthworms. Animals began diversifying at around 453 MYA, and many of the essential groups of invertebrates deviated from one another. Fossils of the invertebrates are found in different categories of sediment from the Phanerozoic (Segner, H., et al. 305).
Invertebrates developed from single-celled microorganisms. When it comes to the fossil record of invertebrates, those with soft bodies such as jellies, flatworms, ribbon worms, hydras and round worms are not frequently fossilized. As a result, most fossil hunters depend on microfossils, trace fossils or chemo fossil remains when exploring the prehistoric creatures. Large and hard-bodied invertebrates are normally preserved as large macrofossils. Invertebrates embrace the majority of life on this planet with approximately 95 percent of all animal species (Grzimek, MacLeod, Archibald, Levin, & Blanchfield 23).
They perform important roles to the planet such as in food webs and in maintaining the ecosystem, as pollinators and recyclers. Pollination by insects like flies, butterflies, bees, and beetles plays an essential role in the survival of many plants, human survival and also in the agricultural industry. Termites, burying beetles, dung beetles and other different species of flies do the recycling which helps in the maintaining the health of the environment. They also reduce the spread of diseases and discharges nutrients to be used again in the environment. Most of the invertebrates also act a source of food in different cultures, such as lobsters, shrimps, crabs, beetles grubs and different types of caterpillars. They also produce other useful products such as honey, dyes, wax and silk. They play a major role for zoos because they are used to educate, research and in conservation of species, habitats, and ecosystem (Grzimek, MacLeod, Archibald, Levin, & Blanchfield 39).
Vertebrate are animals which have an internal skeleton or spinal cord which is surrounded by bone. They originated about 525 million years ago during the Cambrian explosion, which gave way to the rise in organism multiplicity. The earliest known vertebrates are the Myllokunmingia and the Haikouichthys ercaicunensis. These two groups had the basic vertebrate body plan which consisted of rudimentary vertebrae, a notochord and a distinct head and tail. These early vertebrates did not have jaws and relied on filter feeding close to the seabed (Segner, H., et al. 305).
The first vertebrates with jaws appeared in the late Ordovician and were popular in Devonian. It is during Devonian that all jawless fishes demised as well as save for hagfish, lampreys and also a group of armored fish that took over much of the late Silurian. Reptiles appeared in the Carboniferous period. Ebony fishes became dominant during Mesozoic. The dinosaurs gave rise to the bird in the Jurassic. After the dinosaurs had demised at the end of Cretaceous, there was the expansion of the mammals which had developed from a collection of synapsid reptiles, throughout the late Triassic time (Raper 89).
Both vertebrates and invertebrates have a global similarity because they all have a notochord which is present at some stage of their development. Notochord is replaced by a sequence of linking bones which later differentiate the two. Both vertebrates and invertebrates belong to the same kingdom, Animalia. Both vertebrates and invertebrates belong to the same chordate pylum. Chordate is divided into various classes, reptiles, amphibians, amphibians, birds and mammals. To some extent, both vertebrates and invertebrates depend on each. Generally, vertebrates depend on invertebrates since most of them are directly used as food, helps in decomposition, pollination of plants, stabilizing the ecosystem and also assist in pest control (Raper 91).
The differences between vertebrates and invertebrates are;
- Vertebrates have a backbone with a spinal cord while invertebrates do not have any.
- Invertebrates show either bilateral or radial symmetry while vertebrates are always bilaterally symmetrical.
- The diversity is remarkably high among the invertebrates compared to vertebrates.
- Vertebrates have bigger and stronger bodies and have a higher speed in movement compared to invertebrates.
- Invertebrates have a good adaptability due to their simplicity compared to vertebrates because of the specialization.
Types of invertebrates include;
- Sponges: for example, Agelas conifer and the Brown Tube Sponge.
- Arthropods: for example, insects, arachnids, crustaceans, centipedes, millipedes.
- Cnidarians:
- Mollusks: for example, snails, octopus, oysters, slugs and chitons.
- Worms: for example, flatworms, roundworms, segmented worms and rotifers.
- Echinoderms: for example, starfish, sea urchins and sea cucumbers.
- Coelenterates: For example, jellyfish, sea anemones and corals.
Types of vertebrates include;
- Fish: for example, tilapia,
- Amphibians: for example, frogs, toads, caecilians and salamanders.
- Reptiles: for example, crocodiles, snakes, lizards, turtles and alligators.
- Birds: for example, penguins, and ostriches.
- Mammals: for example, humans, elephants, tiger, buffalo.
Both invertebrates and vertebrates have that unique feature which unites all of them. At some stage in their development, they develop a flexible supporting rod known as notochord which runs through the length of their bodies. At some point in their development, majority of the of the chordates’ notochord is replaced by a sequence of interlocking bones referred to as vertebrae. These bones distinguish the vertebrates and invertebrates (Patient, and James 418).
Both invertebrates and vertebrates vary from each other in several ways. They vary in physical characteristics, where vertebrates appear to be large in size and have a higher speed of movement. They also differ in habitats since invertebrates have a good adaptability than vertebrates because of their simplicity. Both of them vary in classification. Invertebrates make up to almost 96 percent of all the population in the entire animal kingdom. The two also differ in the way they adapt to the environment. Invertebrates react quickly to changes in their environment compared to vertebrates which react almost completely by instinct (Patient, and James 420).
There are numerous new invertebrates and vertebrate’s species discovered every year in all parts of the world. For example, many species were found in New Guinea, which included a fanged frog, blue lizard and a bright yellow snail among many more. The extinction of vertebrates and invertebrates happened over 440 million years ago, and it largely affected the marine families. Invertebrates dominate the largest percentage of all described animal species which is almost 96 percent while the vertebrates only dominate a very small number of only 4 percent.
Works Cited
Grzimek, Bernhard, Norman MacLeod, J D. Archibald, Phillip S. Levin, and Deirdre S. Blanchfield. Grzimek's Animal Life Encyclopedia: Extinction. Detroit: Gale/Cengage Learning, 2013. Print..
Patient, Roger K., and James D. McGhee. "The GATA family (vertebrates and invertebrates)." Current opinion in genetics & development 12.4 (2002): 416-422.
Raper, Jonathan A. "Semaphorins and their receptors in vertebrates and invertebrates." Current opinion in neurobiology 10.1 (2000): 88-94.
Segner, H., et al. "Identification of endocrine-disrupting effects in aquatic vertebrates and invertebrates: report from the European IDEA project." Ecotoxicology and environmental safety 54.3 (2003): 302-314.
