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
Name some characteristics of brachiopods, a lophotrochozoan.
Solitary marine animals, live attached to substrate
Two-part shell, connected by ligament
Feed using lophophores
Gametes released into water
Planktonic larvae
Which other animal do brachiopods resemble?
Bivalve mollusks, but they evolved independently of them
What are the two parts of the brachiopod shell?
Dorsal and ventral
How do brachiopods attach themselves to a substrate?
Using a stalk
What are some characteristics of annelids, a lophotrochozoan?
Clearly segmented
Separate nerve ganglion controls each segment
Thin permeable body wall
An annelid is clearly segmented. How are these segments established?
A coelom in each segment is isolated from the coelom in other segments by septae, or barriers.
What are septae?
dividing walls or membranes
What is the function of a thin, permeable body wall in annelids?
it is useful for gas exchange by diffusion, and also restricts annelids to aquatic or moist habitats, because they easily dry out.
What are the two major annelid groups?
Polychaetes and Clitelllates
What are the two types of clitellates, a major annelid group?
Oligochaetes and leeches
What is one type of polychaete, a major annelid group?
Pognophorans
Name some characteristics of polychaetes, a major annelid group.
Mostly marine, burrow in soft sediments
One or more pairs of tentacles
Parapodia
Setae protruding from parapodia`
What is the function of tentacles in polychaetes?
Prey capture and filter feeding
What is the function of parapodia in polychaetes?
gas exchange and movement
Where on polychaetes are setae found?
Found protruding from parapodia
What are parapodia in polychaetes?
Appendages that are an extension of the body wall
Increased surface area useful for gas exchange
What are setae in polychaetes?
Stiff bristles that provide grip
What are pognophorans and where do they live?
They are polychaetes, a major annelid group, and tube worms.
They live near deep hydrothermal vents in tubes made of chitin.
What are two characteristics of pognophorans? (tube worms)
Hemoglobin in their tentacles impart red color
They have no digestive tract
Pognophorans have no digestive tract. What are the two ways they acquire nutrition?
Dissolved organic matter diffuses into their body
They have endosymbiotic bacteria in a specialized organ called the trophosome. These endosymbiotic bacteria fix carbon using energy from the oxidation of hydrogen sulfide (H2S).
What are the two types of clitellates?
Oligochaetes and leeches
Name three characteristics of oligochaetes.
No parapodia, eyes, or tentacles
They have a few setae
They are all hermaphroditic
One example of oligochaetes are ____________.
earthworms
Name 5 characteristics of leeches.
Lack parapodia and tentacles
Undivided coelom
Suckers at the ends
They can live in freshwater or on land (terrestrial)
Parasites that feed on blood and secrete an anticoagulant where they bite
What are mollusks?
The most diverse group of lophotrochozoans.
What are the 3 main components of a mollusk body plan?
Foot, visceral mass, and mantle
What is the mollusk’s foot?
Large, muscular structure, originally for locomotion and support of internal organs; has been modified in different groups.
What is the mollusk’s visceral mass?
Heart, digestive, excretory, and reproductive organs.
What is the mollusk’s mantle?
- Fold of tissue that covers organs in the visceral mass; secretes the calcareous shell.
- Extends beyond the visceral mass to form the mantle cavity. Contains gills for gas exchange.
What are the 4 major clades of living mollusks?
Chitons
Gastropods
Bivalves
Cephalopods
Name some characteristics of chitons, a major clade of living mollusks.
Eight overlapping calcareous plates, surrounded by a girdle, protect the organs and muscular foot.
Most are marine omnivores that scrape algae from rocks with a radula (a rasping structure).
They cling tightly to rock surfaces with the large, muscular foot
Gastropods are a major clade of living mollusks. What are some examples of gastropods?
Snails, slugs, nudibranchs, limpets, and abalones
What is a characteristic that most gastropods share?
Most move by gliding on the foot, but in a few species it is a swimming organ.
What are some characteristics of nudibranchs and slugs, which are both gastropods?
Nudibranchs and slugs have lost their shells. Many are toxic and have brilliant colors for warning (aposematic coloration). Others have camouflaged coloration.
What is aposematic coloration?
Brilliant warning colors.
Which two mollusks are the only ones that are terrestrial?
Land snails and slugs
In land snails and slugs, which are the only mollusks that live in terrestrial habitats, the mantle is modified into a _____________________.
highly vascularized lung
Bivalves are a major clade of living mollusks. What are some examples of bivalves?
Clams, oysters, scallops, and mussels.
What are some characteristics of bivalves?
Have hinged, two-part shells. Many use the foot to burrow into mud or sand.
Feed by bringing water in the incurrent siphon and filtering food particles with large gills; water exits through the excurrent siphon.
Cephalopods are a major clade of living mollusks. What are some examples of cephalopods?
Squids, octopi, and nautili
What are some characteristics of cephalopods?
High degree of mobility: water can be forcibly ejected from the body cavity, creating “jet propulsion.”
Head has complex sensory organs. Eyes are comparable to vertebrates.
Arms and/or tentacles are used for movement and prey capture.
Many early cephalopods had ____________ shells.
chambered
The only living cephalopod with a chambered shell is the ____________.
Nautilus
Most cephalopods retain a small ________________ that provides internal support. Octopi lack these, which allows them to pass through small openings.
internal shell
