Investigate invertebrates
These animals are not the same as chordates
You will find these phyla are known as animals without backbones
Backbeat for those without a backbone.
No backbone growin' no backbone

You know a protozoan is a microscopic creature, a single cell feature
An animal that lives as the most primitive
Oh you are so unicellular, as a protozoan, comin', goin', in the ocean
Swimmin' little fella propelled by flagella
To understand their body plan, define 'em with a phylum Protozoan
Backbeat for those without a backbone
No backbone growin' no backbone

If you met a metazoan you would know him, how you tell
It's an animal that's growin' into something multi-celled
For the simplest of these species take a plunge
To the bottom of the ocean, start lookin' for a sponge! Spongin' Porifera
This phylum has lived here 600 million years
To understand their body plan, define 'em with a phylum Porifera
Backbeat for those without a backbone
No backbone growin' no backbone

Arthropods are jointed limbed, with a head and thorax and abdomen
Their hardened skin is an exoskeleton and marine arthropods are crustaceans
There are quite a lot of other land arthropoda, many footed centipede, chilapoda
Diplopada, a millipede, one thousand feet millin' round feedin' on decaying plants
Scorpion, tick, mite, spider, insect and the like made of segments called somites, it's their body plan
Their life cycle often is a change through metamorphosis
Transforming, many do, into something born anew
To understand their body plan, define 'em with a phylum Arthropoda
Backbeat for those without a backbone
No backbone growin' no backbone

If you want to get to know a Nematoda, it's a worm, squirmin' for a bite, a parasite
Now it can't wait to satisfy an appetite inside of every vertebrate
Round worm, pin worm, whipworm, guinea worm
Live in your intestines, feed on yummy yeast
Some are predators, on living things they love to feast
Billions in the soil, in the water we are told
There could be a half a million different kinds of Nematodes
To understand their body plan, define 'em with a phylum Nematoda
Backbeat for those without a backbone
No backbone growin' no backbone

Annelida we will learn, is the body of a worm
Segmented and cylindrical, it burrows down into the shade or lives in tubes that it has made
The earthworm one of the nine thousand species using bristles, call 'em setae
When it gets a notion to hold on tight or crawl in wormy locomotion
With male and female parts, mating works alright, Annelida reproduce as hermaphrodites
To understand their body plan, define 'em with a phylum Annelida
Backbeat for those without a backbone
No backbone growin' no backbone
Of all the living animals discovered to date, 95% are invertebrates