PHYLA NEMATODA

By: Alex Palasz, Alex Roszczyk, Danielle Perri, Vicky Moskal

GERM LAYERS

3 germ layers: endoderm, mesoderm, and ectoderm.

Nematodes are considered triploblasts because they have three germ layers.

SYMMETRY

Bilateral symmetry

COELOM

Nematodes have a pseudocoelom because they have a body cavitiy that is lined with mesoderm and endoderm as opposed to just mesoderm.

DIGESTIVE TRACT

Tube-like digestive tract with a mouth and an anus.

CEPHALIZATION

Centralization of nerves in the head region.

Nematodes have a rear nerve ring around the area of the pharynx.

SEGMENTATION

Non-segmented.

SKELETON & APPENDAGES

The hydro-skeleton maintains high water pressure in the nematode to keep its structure.

They have a tough elastic outer-cuticle that is used for movement.

The flexibility of the muscles combined with the hydro-skeleton allows the nematode to swim in a “whip-like” movement.

CIRCULATORY SYSTEM

None

The outer-cuticle of the nematode allows nutrients and necessary materials to flow into the nematode and through its body through diffusion.

RESPIRATORY SYSTEM

None

The outer cuticle is permeable to water and gasses so it is used to breathe and absorb necessary nutrients.

REPRODUCTION

Nematodes reproduce sexually.

They reproduce through internal fertilization. In most species of nematodes, organisms are separated by sexes and the females tend to be larger.

MALE VS. FEMALE BODIES

HABITAT

Nematodes usually inhabit water, soil, and bodies of other plants or animals.

As many as 1 million nematodes inhabit one square yard of soil.