Chapter 14 - Flatworms

Notes for Chapter 14:
Platyhelminthes (Flatworms)

Click link to return to Lecture Schedule
or back to Chapter 13
or ahead to Chapter 15 (lab only)
or ahead to Chapter 16 (will be covered Oct. 1, 3)
Optional trip to Zzyzx is coming up! Oct. 6-7.
Images from previous years: 1 - 2 - 3 - 4

Chapter 14 Assignment:

Ch. 14: 281-296, 300-302; RQ-14: 1-3, 8-10, 13

Introduction:

I. Platyhelminthes
More Links

Source of images or here © Wolfgang Seifarth

Featured organism: The marine polyclad flatworm,
Thysanozoon nigropapillosum
More Beautiful Free-living Flatworm Links: 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8

Topics

planuloid hypothesis
Types of interspecific interactions:
competition/predation/symbiosis
Types of symbiosis:
commensalism/mutualism/parasitism (also a type of predation)
complex life histories:
intermediate/definitive hosts
Trematoda (flukes) and Tapeworm life cycles
Parasite adaptations

Types of interspecific interactions

mutualism (+/+): both species benefit
commensalism (+/o): one species benefits, no affect on other
competition (–/–): bad for both species
predation (+/–): predator benefits at expense of prey

Types of interspecific interactions (another approach)

true predator – few prey taken per feeding
grazer - many prey per feeding, nonfatal
parasite – few hosts in lifetime, usually nonfatal
parasitoid – larval develops inside host, fatal

Parasite Categories

1. By size
–micro (Plasmodium – malaria)
–macro (liver flukes, tapeworms)
2. By habitat
–ecto (lives on)
–endo (lives in)

Parasite Adaptations

1. Adhesive organs (attach to host)
2. Sense organs reduced
3. Modified nutrient uptake
– tapeworms have reduced digestive tract, tegument absorbs material
– food storage areas
– suckers, suck body fluid
4. Most energy goes for gametes
5. Transfer mechanisms, host to host
– complex life cycles
– motile larval stages
– resistant gametes or zygotes
6. Host recognition mechanisms - complex chemical, behavioral,
and physiological signals between host and parasite
7. Coevolution is striking

Flatworm Terms (Study!):

epithelium (ectoderm)
parenchyma (mesoderm)
acoelomate
ocelli
rhabdite
tegument
syncytial
complex life histories
hermaphroditism
intermediate/definitive hosts
Trematoda (flukes): 1 - 2 - 3
miracidium: 1 - 2 - 3 - 4 , sporocyst, rediae: 1 , cercariae: 1 , metacercariae
opisthaptor (Monogenea)
scolex (Cestoda: 1 - 2 - 3)
proglottid

source of image of Schistosoma life cycle

Click link to return to Lecture Schedule
or back to Chapter 13
or ahead to Chapter 15 (lab only)
or ahead to Chapter 16 (will be covered Oct. 1, 3)