PSEUDOCOELOMATE PHYLA

CHARACTERISTICS

• Pseudocoelom• space between gut and

mesoderm parts of body wall

• space filled with fluid• for differentiation of

systems

• storage of waste products

• used as hydrostatic skeleton

CHARACTERISTICS• Cuticle• acellular outer covering, over epidermis• for protection against water loss or gain• resistant to environmental chemicals

• Systems• Don’t have:• circulatory system• respiratory system• true skeletal system

• Do have:• Reproduction: usually dioecious• excretion: protonephridia• digestive: complete• muscles: longitudinal only• nerve: ladder like with cerebral ganglia• hydrostatic skeleton: for movement

CHARACTERISTICS

PSEUDOCOELOMATE PHYLA

• Major – Nematoda

– Rotifera

– Gastrotricha

– Nematomorpha

– Acanthocephala

• Minor (see text)– Kinorhyncha

– Loricifera

– Priapulida

– Entoprocta

Nematoda(roundworms)

• numerous, slender, cylindrical

• Unsegmented

• found in all types of habitats, terrestrial, marine, freshwater

• dioecious

Nematodes - Characteristics

• Sense organs – Bristles for Chemoreception– Amphids – unique

• Digestive system – Complete

• Excretion– Free living Marine species – Renette gland– Freshwater and Terrestrial - Tubular

Ascaris lumbricoides(intestinal roundworm)

• - 64% of SE is infected• may produce 200,000

eggs/day• life cycle

– ingested by humans as eggs– intestinal larvae get into

blood– carried to lungs– get coughed up and

swallowed– adult develops in small

intestine– eggs released through feces

Ascaris

Necatur americanus(hookworm)

• 1910 40% of SE infected• 1963 4% infected• life cycle

– penetrates skin on bottom of feet– gets into blood and goes to lungs– coughed up and swallowed– attached to intestine– produce anticoagulant and feed on blood

Trichinella spiralis(trichinosis)

• very bad to contract• get it from eating

undercooked pork• humans not in natural cycle• in humans encysts in

muscles, causes aching• life cycle

– one host– larvae feed in intestine– adults live in intestine

Enterobius vermicularis(pin worm)

• in 46% of population• most common parasite in humans

in world• life cycle

– adults in folds of anus

– female emerges at night to lay eggs

– eggs get under nails, are also airborne

– larvae develop in digestive tract

– not very serious, more of a nuisance

Filariasis

Dog Heartworm

Phylum Rotifera(rotifers)

• have a corona with cilia, like norelco shaver head

• no cilia elsewhere• with forked “foot”

with cement glands for attachment

• complex digestive structures such as mastax

Rotifer Reproductiondioecious

• Parthenogenesis

Phylum Gastrotricha(Gastrotrichs)

• ventrally flattened with bands of cilia

• also have adhesive glands on foot

• with spiny, scaly or warty cuticle

• no corona or mastax, etc.• hermaphroditic, male

system in some reduced• reproduction similar to

that of rotifers

Phylum Nematomorpha(horse hair worms)

• larvae parasitic in insects like grasshoppers• adults aquatic, but do not feed• life cycle

– eggs ingested by grasshopper

– larva develops in gut

– emerges when host near water

– develops into adult

• dioecious

Phylum Acanthacephala(spiny headed worms)

• have characteristic spiny proboscis• have no digestive tract• life cycle

– larvae found in arthropod, such as insect– all adults endoparasites in guts of vertebrates

• Dioecious• Acanthor Larva