Pseudocoelomates

Pseudocoel = original blastocoel of embryo

allows

1)

2)

3)

Body wall of epidermis dermis muscles surrounding pseudocoel

In General:

Complete Digestive Tract = mouth to anus

Triploblastic

Bilateral

Lack Circulatory and Respiratory Organs

Protonephridia and canals for excretion

Phylum Rotifera

ciliated corona

body non-ciliated with cuticle

Syncytial epidermis

Digestive system - muscular pharynx or mastax

Trophi -

Salivary and gastric glands

Stomach -

Excretory system - Protonephridia tubules with flame cells - common bladder. All empty into a cloaca (common chamber)

Nervous system - Bilobed Brain

Reproduction - dioecious and sexually dimorphic.

Mictic or amictic

1. Amictic female produces a 2N egg by mitosis that develops into a 2N amictic female that repeats the cycle

Egg not fertilized - hatch into haploid males that produce sperm

2. Mictic female produces haploid eggs

Egg fertilized producing 2N dormant egg

Eutely - Nuclear Constancy: precise genetic control of nuclear division which halts when precise number of nuclei is reached.

Phylum Nematoda - roundworms

Characteristics:

cylindrical shape

Cuticle is thick - collagen; contains hydrostatic pressure exerted by fluid in pseudocoel.

Only longitudinal muscles present; cuticle serves function of circular muscle group.

Most dioecious and sexually dimorphic - males smaller and have copulatory spicules on posterior end

Ascaris lumbricoides

Hookworms

Pinworms

Filarial nematodes --> microflilariae -->Mosquitoes --> pass to blood of another human.

Elephantiasis - blockage of the lymph nodes and ducts. This results in the accumulation of lymph and swelling of the tissues.

another filarial worm produces - river blindness (onchocerciasis); the black fly is the vector (Africa and S. America); the world's second leading infectious cause of blindness

Most common filarial worm in the US - dog heart worm; mosquito also the vector