General Parasitology Exam 2 Info

Phylum - Platyhelminthes

Platyhelminthes (flatworms): simplest bilaterally symmetrical animals

- most = parasitic

- acoelomate body plan (no body cavity; only gut); rarely has anus

Domain: Eukaryota

Kingdom: Animalia

Phylum: Platyhelminthes

Class: Turbellaria

Monogenea

Cestoidea

Trematoda

Subclass: Digenea

Aspidogastrea

Domain: Eukaryota

Kingdom: Animalia

Phylum: Platyhelminthes

Class: Turbellaria

Monogenea

Cestoidea

Trematoda

Subclass: Digenea

Aspidogastrea

- triploblastic (composed of three fundamental cell layers) Ex. mesoderm, ectoderm, & endoderm

- dorsoventrally flattened (greater surface area to respire by diffusion)

- tegument (surficial covering of a multicellular organism, an integument)

- parenchyma (loosely arranged mass of fibers and cells of several types)

Subclass: Digenea

Dignetic trematodes (flukes): a subclass within the class Trematoda

- digeneans parasitize all classes of vertebrates

- develops in at least two hosts

- first host is a mollusk (most often a gastropod) or very, rarely an annelid

Digenea: Form and Function

Body Form

Most dorsoventrally flattened and oval in shape; others as thick as they are wide [L ranges 1mm-6cm]

Oral sucker: muscular sucker that surrounds the mouth

Acetabulum: ventral sucker of a fluke

Distome: fluke with two suckers, oral and ventral

Monostome: fluke that lacks a ventral sucker

Amphistome: flukes with a ventral sucker located at the posterior end

Tegument: superficial covering of a multicellular organism, an integument

- distal cytoplasm: anucleate layer of cytoplasm above a “sunken epidermis”

- cytons: cell bodies containing nucei; lie beneath superficial muscle layer

- internuncial processes: channels that connect cytons to distal cytoplasm

- syncytial: describes the continuous distal cytoplasm with no intervening...