Blastopore forms Mouth
Ecdyozoa (9 phyla)
Lophotrochozoa (17 phyla)
ciliated tentacles / band of cilia in larval stage
• False body cavity not lined with mesoderm
• Bilateral symmetry, triploblastic
• Epidermis (often syncytial).
• Muscles surround pseudocoel (Longitudinal)
• Digestive, excretory and reproductive systems
• Perivisceral fluid—Hydrostatic skeleton
• Simple circulation
• Storage for waste
• Complete digestive tract (exception acanthocephala)
• Eutely in some species
Phylum Rotifera—”Wheel bearer”
~ 2000 spp. Cosmopolitan
Some Epizoic and Parasitic
Body consist of Head, Trunk and Foot
Corona and Mastax
Germovitellaria produce yolk and oocytes
Cloacal bladder- Pair of Protonephridial
tubules with flame bulbs
1 to 4 toes—Pedal glands
Asexual and Sexual Repr.
Males not known in many spp.
Amictic eggs (2n) only
Other species produce
Amictic AND Mictic (n) eggs
Phylum Acanthocephala—Spiny Headed Worms
~ 1100 spp. Cosmopolitan. 2 mm to 1 m !!! Ouch!
Adults endoparasites of vertebrates
Molecular evidence—highly modified rotifers!
Proboscis with recurved spines
No digestive tract
Syncytial tegument with crypts
Lacunar system—distribution of nutrients?
Excretion across tegument
Zygote develop into acanthor larvae
Cystacanth larvae infective to def. host
Parasite induced changes in Host behavior
Phylum Gastrotricha—”Belly Hair Worms”
~ 460 spp. FW and Marine
Bristly or scaly
Glide on cilia
Male system non-functional
Phylum Entoprocta—“Within Anus”
~ 100 spp. Most Marine
Stalked and sessile
Colonial or solitary
Body is cup shaped with ciliated tentacles
Mouth and Anus within “cup
Monoecious, dioecious, or protandrous herm.
~ 12,000 described spp. estimate: ~500,000 spp
Cosmopolitan, all habitat and climatic regions
Free living or parasites of animals and plants
Non living Cuticle (growth via molting)
No cilia or flagella
Most dioecious, internal fertilization
Sperm lack flagella !!! WHAT???
Gland cells &/or Canal system. NO flame cells
N.C., circa 1913
Complete digestive system with Muscular pharynx
Phylum Nematoda—Form and Function
Digestive and Reproductive systems
in fluid filled pseudocoel
High hydrostatic pressure
Cuticle primarily collagen secreted by
Below Hypodermis, longitudinal muscles only
Cephalization near Pharynx
2 nerve chords (ventral/dorsal)
Some interesting (i.e. parasitic) nematodes
Ascaris lumbricoides, Human roundworm
Found in 20% of the world’s pop.
Adults— Abdominal problems, blockage
What can you do?
Adults in small intestine (12-20 mm)
Feed on blood!!
Eggs passed in feces hatch in the soil
Rahbditiform Larvae (feed on bacteria)
Filariform Juveniles burrow through skin
Migration--blood-lungs-intestine Copulatory bursa
Mental retardation in children
Most common helminth parasite in the U.S. (30% in children)
Live in large intestine and cecum
Females migrate to the anus to lay eggs
Females release live microfilariae in blood and lymph
8 species of filarial worms known to parasitize humans (tropics)
Ex. Wuchereria bancrofti causes Elephantiasis
Adults in lymphatic system cause its inflammation and obstruction
Microfilariae picked up by mosquito with blood meal, develop and infect
new host when mosquito bites uninfected individual
Dirofilaria immitis—Dog Heart Worm
Most common filarial nematode in the U.S.
Insect vector = mosquito
Phylum Nematomorpha—Horse Hair Worms
~250 spp. Worldwide
Free living as adults
Parasitic as juveniles in arthropods
Emerge from arthropod only near water !
Other Ecdysozoa Phyla
All marine dioecious worms
~179 spp., < 1 mm, mud dwellers
~9 spp., 12-15 cm, predators
~100 spp., live in marine gravel