Mr. Bastin - Zoology and Botany - Flatworms and Roundworms

Flatworm Taxonomy

Domain: Eukarya

Kingdom: Animalia

Phylum: Platyhelminthes

Flatworms Include

• free-living Turbellaria,

• parasitic flukes,

• parasitic tapeworms

Flatworm Structure

• bilateral symmetry

• Cephalization

• Triploblastic

• Acoelomates

• Have several distinct organs

Triploblastic

3 tissue (germ) layers

- ectoderm

- mesoderm

-endoderm

Flatworm Feeding/digestion/excretion

The gastrovascular cavity serves as the mouth and anus

Acquire food via the pharynx

-food digested by the gastrovascular cavity

-circulatory system not needed as the body is thin

flame cells

(Flatworm)

-help with osmotic balance

fluids down tubes, out through pores

Flatworm Sensory/response

• They have ganglia but no brain

• Nerve cords run along the sides of the body

• Eyespots (ocelli) near the head detect changes in light

• They have sensory receptors all over the body

Parasitic forms typically have a less complex?

nervous system, they get everything they need from their host and they don't need protection from predators (no predators)

Flatworm Movement

• use cilia to glide through water or over surfaces of film of mucus

• mucus aids in traction

• Muscular contractions for swimming/twisting

Flatworm reproduction

both asexual and sexual

asexual - An organism splits through fission - each part becomes new individual

sexual - mutual insemination - sperm/eggs from both parties

penis jousting - winner deposits sperm on other

Flatworm classes

Turbellaria, Trematoda, Cestoda

Turbellaria

(flatworm class)

free-living, mostly aquatic

ex. planaria

Trematoda

• (flatworm class)

• -a.k.a. flukes

• -all parasitic

• Most use suckers to attack to host's organs

• Life cycles include multiple hosts

• asexual phase within the intermediate host

• sexual phase within the final host

Cestoda

(flatworm class)

a.k.a. tapeworms

from 1 mm to 19 m long

live in the host's intestines and absorbs food through body wall

Roundworm Taxonomy

Domain: Eukarya

Kingdom: Animalia

Phylum: Nematoda

Roundworm Basics

-a.k.a. Nematodes

up to 1 million in 1 m^3 soil

Some are free-living, others are parasitic

1/2 live in water

Structure Roundworm

• bilateral symmetry

• Triploblastic (three tissue (germ) layers) - ectoderm, mesoderm, endoderm

• Pseudocoelomates

• Distinct organs and organ systems

Pseudocoelomate

(roundworms)

-have "false coelom

>cavity between endoderm and mesoderm partially lined w/ tissue

Roundworm Feeding/digestion/excretion

• one-way digestive tract running from mouth to anus (two openings)

• are protostomes (mouth made then anus)

• diet varies by worm

• diffusion carries nutrients/wastes through the body

Protostomes

(for roundworms)

-mouth formed 1st, anus 2nd

-most invertebrates

Roundworm Sensory/Response

simple nervous system of ganglia (group of nerve cells)

Roundworm Movement

• muscles together with fluid in the pseudocoelom function as a hydrostatic skeleton

• swim in water or push through soil

Roundworm Reproduction

• sexual reproduction

• sexually dimorphic (individual is male or female)

• females are larger

Hookworm

(roundworm)

-1/4 of the world population infected

Pinworm

(Roundworm)

-25% of you probably had as a kid

Ascarid worms

(Roundworm)

-impact 1 billion people worldwide

-cause malnutrition

Trichinella (pork worm)

(roundworm)

• causes trichinosis

• from eating undercooked pork

Filarial worms

(roundworm)

• live in blood/lymph vessels

• transmitted via biting insects