As far as binomial nomenclature goes in biology, the earth’s largest phylum, arthropoda, is traced right after the precise classification in kingdom Animalia. As a result, all organisms in this phylum are considered animals. They include crustaceans, millipedes, centipedes, spiders and insects (Whittington, 1979).. Species vary to over one million in number and account for over 80% of the living animals on earth.
Among the five classes mentioned here, insects have over the years proved to be the focus of success in the phylum. This is due to certain characteristics that have continuously given them unbeatable advantages over their counterparts. One such characteristic is the possession of an exoskeleton. A small animal with an exoskeleton proves to be a clear-cut advantage. This is because small size and exoskeletons are directly entwined as far as the biological dynamics are concerned. Large size would for instance call for thicker and larger exoskeletons which would be cumbersome and bulky.
One more advantage is the minimal resources required for growth and reproduction. This is backed up to a great degree by the small size of insects. There are cases that feature insects living in a single plant for their entire lifespans as food required is so minimal. Not only that, their small size again offers them an added benefit of predator avoidance. Insects can hide almost everywhere, be it under leaves, beneath tree barks, in cracks of rock and even behind blades of grass.
As if that is not enough, insects are the only invertebrates that fly. This presents a very effective mode of getting away from predators. The flight of the insects employs incredibly efficient principles of aerodynamics which are further reinforced by thorax elasticity. Due to this, insects can remain airborne in remarkable periods of time.
Adaptability, big reproductive potentials and short metamorphoses all add up to gauge the insect at a high scale in the animal hierarchy of success. Despite this, the size of insects has remained small through the years. The biggest known insect weight is only 115 grams; that of a goliath beetle. It is rare in most cases to come across such weight in insects. Most insects relatively weigh below 50grams. This is due to certain known and hypothesized reasons. One is an unavailability of amounts of oxygen in the atmosphere that could boost growth of insects to giant sizes. Scientists claim that more oxygen levels could see insects grow to giant sizes. Another significant and provable reason is the presence of their exoskeleton. As discussed earlier, if large animals could possess exoskeletons, then they would be limited biologically in other ways (Whittington, 1979). Natural selection has therefore chosen the best optimal option. The exoskeletons limit the growth of insects beyond certain sizes that if exceeded could lead the insects success scaled down to a failure.