590mya Protosomes

INSECTS, SPIDERS, CENTIPEDES, LOBSTERS, CRABS, SHRIMP, MOLLUSKS, ROUNDWORMS, FLATWORMS, FLUKES.

Just a single class in the sub-kingdom of protostomia, the Insecta, represents three quarter of all animal species on Earth. The great divide between protostomes (meaning 'mouth first') and deuterostomes (meaning 'mouth second') was devised by comparative embryologists based on the way animal embryos diverge after gastrulation where the blastula (a hollow ball of cells) indents to form a cup. In the sub-kingdom of protostomia, the indentation eventually becomes the mouth. In deuterostomia which includes humans, the indentation eventually becomes the anus; the mouth is formed later. An extremely large variety of animal phyla constitute protostomia, including annelid worms (e.g. garden earthworms), flatworms (e.g. tapeworms and flukes), molluscs (e.g. snails, oysters, ammonites and octopuses), and arthropods (e.g. insects, crustaceans, spiders and centipedes). Together with their sister clade, Deuterstomes to which we belong, they make up all the bilaterally symmetrical organisms we see on earth today.

As this early differentiation is based on a cryptic embryological difference, it is difficult for us to identify with many protostomes and so our harvesting of wild stocks of crustaceans is more appetizing than crunching into fried spiders or locusts which are delectable snacks in some countries.  Insect larvae (black soldier fly maggots) are a growing source of protein for livestock feeds and are poised to become a protein supplement flour for humans.  The recent possibility of farming octopuses puts our moral ethics in direct conflict with domesticating one of the most intelligent cephalopods on the planet.