Chapter 8: Worms Flashcards
____ refers to loosely elongated, bilateral invertebrate animals without appendages
Worms
How many phyla of worms have acoelomate bodies?
2 phyla
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
How many digestive spaces do acoelomate worms have?
one
What are worms called that have a fake coelum?
Pseudocoelomate
What makes a pseudocoelomate worm?
The cavity is not Completely lined with mesoderm
What are the functions of pseudocoelum?
Provides space for expansion of organs
Water storage
Many pseudocoelomate worms lack a what
true circulatory system
Which two phyla are aceolomate?
Xenoturbellida and Acoelomorpha
Describe Xenoturbellida
Very large, found in deep sea, thick epidermis, subepidermal nerve net
How do Xenoturbellida reproduce?
Sexually
Describe Acoelomorpha
tiny worms, marine and brackish habitats, free living
Xenocoelomorpha are not ______. But all organisms for the rest of the semester are
bilaterians
Protostomia are divided into 2 large _____
clades
What are the two clades Protostomia are divided into?
Ecdysozoa and Lophotrochozoa
Ecdysozoa members possess a ____.
Cuticle, which can be molted
What is an example of Ecdysozoa?
Crabs
Most Lophotrochozoans contain a ___.
Lophophore
What is a Lophophore?
a horseshoe-shaped feeding structure
What is ancestral for Lophotochozoans?
Trochophore larvae
What are the 4 classes of Platyhelminthes?
Turbellaria, Trematoda, Monogenea, Cestoda
What is another name for Phylum Platyhelminthes
flatworms
_____ is the non-parasitic form of Phylum Platyhelminthes
Turbellarians
What do Trematoda, Monogenea, and Cestoda have in common?
They are all parasites
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
