Section 30.2 (Exam 2) Flashcards
Many Lophotrochozoans Have Ciliated Feeding Structures or Life Stages
Name some shared characteristics of bryozoans and entoprocts, aside from being lophotrochozoans.
Colonial; external body walls secrete material that forms a “house.”
Most are marine
Describe some characteristics of a bryozoan colony.
Small individuals, 1-2 mm, connected by strands of tissue
Some species have specialized individuals within the colony for feeding, reproduction, defense, or support
Colonies can form via asexual reproduction of the founding member, up to 2 million individuals
Sexual reproduction: sperm is released and carried to an internal egg.
When a bryozoan egg is fertilized, where does it go?
It is internally developed into a larva, which is then released and finds a new attachment site.
How many individuals can a bryozoan colony have?
2 million
What are some possible specializations of colonial bryozoan cells?
Defense, reproduction, feeding, or support
How big are bryozoan individuals?
1-2 mm
What are the three differences between bryozoans and entoprocts?
Anus location
Where food particles move from
Presence of a coelom
Where is the anus located in bryozoans?
Outside of the tentacle ring, or lophophore
Where is the anus located in entoprocts?
Inside of the tentacle ring, or lophophore
Where do food particles move from in bryozoans?
From the tip of the tentacles to the base of the tentacles
Where do food particles move from in entoprocts?
From the base of the tentacles to the tip of the tentacles
Do bryozoans have a coelom?
Yes, they have a 3-part coelom
Do entoprocts have a coelom?
No
Describe some characteristics of flatworms, a lophotrochozoan.
Dorsoventrally flattened (top and bottom)
Highly branched blind gut
Cephalization and broad bands of cilia for locomotion
Mostly parasites
What effects does being dorsoventrally flattened have on flatworms, and what characteristics have developed because of this?
No gas transport system and every cell is near the surface, so they use diffusion
Why is the blind gut of flatworms highly branched?
Increased surface area for absorption of nutrients
What kind of parasites are flatworms? Name two examples of these parasites.
Endoparasites; tapeworms and flukes.
How come a majority of endoparasitic flatworms’ internal structure are devoted to reproduction and not digestion?
They can absorb nutrients directly from within the host, digestion has little use. Reproduction is necessary for the endoparasite to find a new host and pass on its genes.
What are two serious diseases that are caused by flatworms?
Schistosomiasis and fascioliasis
The complex life cycle of schistosomiasis and fascioliasis which are two serious diseases caused by flatworms cycle between which two hosts?
Freshwater snails and mammals
Name some characteristics of rotifers, a lophotrochozoan.
Live mostly in fresh water
Tiny (50-500 micrometers)
Specialized internals organs and complete gut
Has a pseudocoel
Propel themselves with cilia
How does the pseudocoel in rotifers function?
As a hydrostatic skeleton
How big are rotifers?
50-500 micrometers
What is the corona in rotifers? What is its function?
A ciliated organ on the head. The cilia sweep food into the mouth and mastax.
What is the mastax in rotifers?
An organ that grinds its food
Ribbon worms, or proboscis worms, are lophotrochozoans, and have 1200 species. What are some of their characteristics?
Has a rhynochocoel and a muscular proboscis
Proboscis has sharp stylets
Mostly small, some can be up to 20 metes long
What is a rhynchocoel in ribbon/proboscis worms?
A fluid filled cavity that contains the proboscis
What is the function of the sharp stylets on the end of the ribbon worm’s proboscis?
Piercing prey and releasing toxins
Where do muscle contractions in the ribbon worm expel the proboscis from?
an anterior (frontal) pore