Chapter 8: Worms Flashcards by Erin Wood

____ refers to loosely elongated, bilateral invertebrate animals without appendages

Worms

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How many phyla of worms have acoelomate bodies?

2 phyla

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What is the Parenchymas function and where does it lie?

It is a packaging tissue and lies between the epidermis and digestive cavity lining of acoelomate worms

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How many digestive spaces do acoelomate worms have?

one

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What are worms called that have a fake coelum?

Pseudocoelomate

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What makes a pseudocoelomate worm?

The cavity is not Completely lined with mesoderm

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What are the functions of pseudocoelum?

Provides space for expansion of organs
Water storage

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Many pseudocoelomate worms lack a what

true circulatory system

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Which two phyla are aceolomate?

Xenoturbellida and Acoelomorpha

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Describe Xenoturbellida

Very large, found in deep sea, thick epidermis, subepidermal nerve net

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How do Xenoturbellida reproduce?

Sexually

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Describe Acoelomorpha

tiny worms, marine and brackish habitats, free living

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Xenocoelomorpha are not ______. But all organisms for the rest of the semester are

bilaterians

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Protostomia are divided into 2 large _____

clades

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What are the two clades Protostomia are divided into?

Ecdysozoa and Lophotrochozoa

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Ecdysozoa members possess a ____.

Cuticle, which can be molted

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What is an example of Ecdysozoa?

Crabs

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Most Lophotrochozoans contain a ___.

Lophophore

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What is a Lophophore?

a horseshoe-shaped feeding structure

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What is ancestral for Lophotochozoans?

Trochophore larvae

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What are the 4 classes of Platyhelminthes?

Turbellaria, Trematoda, Monogenea, Cestoda

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What is another name for Phylum Platyhelminthes

flatworms

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_____ is the non-parasitic form of Phylum Platyhelminthes

Turbellarians

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What do Trematoda, Monogenea, and Cestoda have in common?

They are all parasites

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What does Turbellaria contain?

Free-living flatworms

Where are Turbellaria found?

Bottom-dwellers of marine or freshwater or moist places on land

Most monogeneans are ____ meaning they are found on the surface of animals

ectoparasites

What are rhabdites? What is their function

Rod-shaped structures in Turbellarians. They swell to form a protective mucous sheath around the body

Many Turbellarians have ____-____ adhesive organs

dual-gland

What do dual-gland adhesive organs do

Enable quicker attachment and detachment from surfaces

What are the 3 cell types contained in dual-gland adhesive organs?

Viscid gland cells, Releasing gland cells, anchor cells

What do viscid gland cells do?

Fasten microvilli of anchor cells to substrate

What do releasing cells do?

Provide quick, chemical detaching mechanism

What are parenchyma cells? Function?

Form a meshwork that fills space between muscles and organs; noncontractile

Explain the digestion of Turbellarians

Have a Muscular Pharynx that can extend through the mouth. Intestine provides digestive enzymes, from the pharynx food gets sucked into here for intracellular digestion

What is an exception to the Turbellarians digestive system?

tapeworms do not have a digestive system; they absorb nutrients pre-digested by the host

Explain the digestion of Turbellarians

Have a Muscular Pharynx that can extend through the mouth. Intestine provides digestive enzymes, from the pharynx food gets sucked into here for intracellular digestion

The osmoregulatory system in Turbellarians ends in what?

flame cells

What is another name for flame cells

Protonephridia

What is the function of Protonephridia/ flame cells?

To draw fluid through tubules to collecting ducts and use pores to release excess water and wastes from body

True/False: Turbellarians do not have cephalization

False, they do have cephalization

Describe the varieties of nervous systems of Turbellarians

Simple: have subepidermal nerve plexus (similar to nerve net in cnidarians) Some species: have subepidermal nerve plexus and 1-5 pairs of nerve cords that resemble a ladder

What is the brain also called?

cerebral ganglia

A mass of cells arising from nerve cords is the ___.

brain

What are the types of neurons found in the nervous system of Turbellarians?

sensory, motor, association

What are the earlike structures on the sides of the head called?

auricles

What are ocelli?

Light sensitive eyespots common in turbellarians

Some also have ____ for equilibrium and ____ for a sense of water current direction

statocysts; rheoreceptors

Most Turbellarians are diecious/monoecious

monoecious

True/False: Turbellarians only reproduce asexually

False, most produce sexually and asexually

What is an example of internal fertilization

Penis fencing

Explain the structural adaptations of parasitism

Penetration glands, organs for attachment (suckers & hooks) increased reproductive capacity

How many subclasses of Trematoda are there? What is the understood subclass?

3; Digenea

What are the two major components of Subclass Digenea's life cycle

Intermediate and Definitive hosts

What is the intermediate host?

The first host ( may be 2 or 3 of them) Ex. mollusc

What is the definitive host?

The final host; is one where the parasite reproduces sexually Ex. vertebrate

Where are the places that Digenea inhabit?

Digestive tract, Respiratory tract, Circulatory system, Urinary tract, reproductive tract

What is the order of stages in the Digenea's complex life cycle

Adult → Egg→ Miracidium→ Sporocyst→ Redia→ Cercaria→ Metacercaria

What must occur for the shelled embryo/egg to develop?

It must reach water

What happens when the egg reaches water?

It hatches and develops into miracidium, a free-swimming ciliated larva

What must the miracidium do to develop?

Penetrate the tissue of snail

What happens when the miracidium penetrates the tissue of a snail?

It transforms into a sporocyst

What does a sporocyst then do?

Reproduces asexually to form more of itself or goes on to produce Rediae

What does the Rediae then do?

Reproduces asexually to produce more of itself or goes on to produce Cercariae

What does the Cercariae then do?

Penetrates 2nd intermediate host or encysts on vegetation and becomes metacercariae

What happens to Metacercariae?

They are eaten by the definitive host (humans) and grow into adults

Describe the appearance of Phylum Gastrotricha

Bristly or scaly, found in freshwater/marine habitats, Hermaphroditic

What is nonfunctional in many freshwater species of Gastrotricha?

Male reproductive system

How do Gastrotricha reproduce?

Parthenogenesis, where the zygote forms from an unfertilized egg (Asexual)

What is another name for Phylum Chaetognatha?

Arrow worms

Phylum Chaetognatha are adapted for a ____ existence

planktonic

Phylum Chaetognatha are considered ___ because they can dart forward in swift spurts

drifters

What are some characteristics of Phylum Chaetognatha?

Unsegmented body, complete digestive system, well developed coelom, hermaphroditic

What does Phylum Chaetognatha lack?

respiratory or excretory systems