Hookworms
Hookworms are long, thin, unsegmented worms. They have three germ layers that consist of the endoderm (innermost layer), exoderm(outermost layer), and mesoderm (middle layer). Their digestive track is also different than flatworms because the have two openings. The digestive track is particularly interesting because it is a tube within the tube that contains the worm.
Hookworms also contain the Nematoda trait of nervous systems. Nerves run along the whole length of their body and connect in the pharynx acting as a primitive brain. They are able to detect subtle changes because of their nerves. Primitive organs are formed from the small branches of nerve branching forward from the pharynx.
Hookworms also contain the Nematoda trait of nervous systems. Nerves run along the whole length of their body and connect in the pharynx acting as a primitive brain. They are able to detect subtle changes because of their nerves. Primitive organs are formed from the small branches of nerve branching forward from the pharynx.