Flatworms, Nematodes, Annelids and Bristle Worms

This assignment was to create a project showing the 3 types of worms we learned about: Platyhelminthes (flat worms), Nematodes (round worms) and Annelids (segmented worms) (including Polychaetes, or Bristle Worms.

All three types of marine worms have bilateral symmetry and triploblasty (three cell layers: endoderm, mesoderm and ectoderm.)

I created models of each using Tinkercad Software.

This is the flatworm, or platyhelminthes:

Flatworms have a flat body plan, a simple brain called a ganglia at their head end, eyespots that can sense light and dark,  and nerve chords that tell their muscles how to move.  They have only one opening at the end of their pharynx (a tube connecting the gut to the sole opening in their digestive tract, which serves as both mouth and anus.)  The gut spreads throughout the body.

This is a round worm, or nematode:

Round worms have a round cross section.  Thir bodies are smooth and not segmented.  They have two openings in their digestive tract, i.e. a separate mouth and anus.  

This is a segmented worm, or annelid.  It is from Class Polychaeta (a bristleworm).

Annelids have round segmented bodies.  They have well developed digestive, nervous and circulatory systems. They breathe through their skin.

The creature that I modelled is a Polychaete, or "Bristle worm."  It is an annelid that has stiff hairs or setae attached to its body by paddle-like structures called parapodia.

Here is a video of me explaining the models: