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What three characteristics define protostomes?
- Spiral and determinate cleavage
- Mesoderm splits to form coelom
- Mouth develops from blastopore
Trocozoa is defined by what?
Trophore larva- tells us nothing about relationships because it is pleasmorphic
What defines lophophora?
Lophophore- hollow tentacles that surround the mouth used for feeding and sensory
Platyhelminthes is also called what?
What are the four classes of Platyhelminthes?
- Turbellaria- planaria
- Cestoda- tapeworms
What are characteristics of ALL the classes in platyhelminthes?
- Coelom lost
- Organs from the mesoderm fill the insides
- No ciculatory system or respritory system
- Digestive system usually has one opening
What characterizes Ecdysozoa?
What is a synctium?
- A single cell or cytoplasmic mass containing several nuclei, formed by fusion of cells or by division of nuclei
6 characteristics of Turbellaria
- Cephalization (head with sensory organs)
- Excretory system ( protonephridia regulate ionic and water balence and eliminates metobolic wates)
- Sexual reproduction - hermaphroditic, both sex organs discharge gametes into common chamber- cross fertilzation
- Asexual reproduction- fragmentation and regeneration
4 characteristics of Monogenea
- Parasites of fish
- Eggs hatch into ciliated larval stage (onomiacidium) and disperse
- Sexual reproductions ONLY
- One host, mostly external
4 characteristics of trematoda
- Live mostly in digestive system
- Sexual and asexual reproduction
- Life cycle!!!!!!!!!!
5 characteristics of Cestoda
- 1-2 intermediate hosts
- larval or metacestodes live in intermediate host while adult lives in definitive host
- Lack digestive tract
- (flame and tube cells); regulate ionic and water
- balance; eliminates metabolic wastes
- in segments for osmoregultaion and excretion; Annelida; have two openings
- Contain: internal and external opening, collecting tubule, and bladder
- Rotifers are Tetraploid- they have 4 copies of each chromosome. Every gene is duplicated 4 times.
- Copies of each gene are used to patch DNA when one is damaged by desiccation, and every time this happens, genetic diversity may result, because the copies may have changed over time.
- Patching may also remove harmful invasive genetic elements.
Trematoda Life Cycle
- (1) egg, usually operculated-deposited in water via the feces of the definitive host. - reach freshwater, the operculum opens
- (2) ciliated free-swimming larva (miracswims out. - finds a suitable intermediate host, usually penetratessnail, loses cilia and develops
- (3) sporocyst - asexually produces either more sporocysts or a number of rediae
- (4) rediae produce asexually either more rediae or tailed forms called cercariae
- (5) cercariae-emerge -find secondary intermediate host, or the final host or encyst on vegetation, where they are transformed into metacercariae
- (6) metacercariae are juvenile flukes; become adult after being eaten by definitive host
- Eutelic is when an organism can only contain a fixed number of cells (which happens at maturity). Further growth can only occur via cell enlargement.
- Rotifers are eutelic
- reproduce sexually; males are fully developed
- Class of Rotifers
reproduce by cyclical parthenogenesis
facultative sexual reproduction
- Females reproduce asexually mostly: produce diploid
- amictic eggs (cant be fertilized—diploid);
- environmental cues lead to a switch that have daughters
- produce haploid eggs; if haploid eggs aren’t fertilized develop into males
- Males only exist to produce sperm and fertilize eggs
- Diploid embryos can be dormant for many yearsà develop to parthenogenetic females
sexual reproduction provides variation; variants can survive in changing environments
Class of Rotifers
- parthenogenetic females (mostly)
- no males
Class of Rotifers
What are the 6 characteristics of Annelids
- Closed circulatory system (with a heart and blood vessels)
- Mouth, gut and an anus
- Organs housed in a coelom
- Nervous system with a brain
- Metamerization: segmentation, synapomorphy of annelids
Sexual Reproduction of Annelids
- Gonochoric: have males and females (leeches and oligochaetes are hermaphroditic)
- Gametes exit via metanephridia, coelom ducts, or rupturing
- Involves a true trochophore larva (has a band of cilia with which the larva disperses in water)
- Trochophore larva becomes a Nectochaeta
Asexual reproduction in Annelids
- widespread and varied
- budding or fragmentation
- Architomy: regeneration of missing parts AFTER division
- Paratomy: Regeneration occurs BEFORE division
How does metamerization/segmentation influence
asexual reproduction by fragmentation
the fragments need only rebuild certain systems
How does the hydrostatic skeleton work?
It is dependent on the coelom which mediates antagonism between circular and longitudinal muscles; compartments serve has local transport system; space for maturation and nourishment of gametes
- Not a real name because it is paraphyletic
- Parapodia differ from Annelids - numerous chaetae
2 classes of polychaeta
- Errantia- Motile
- Sedentaria- Non-Motile
- ~Clitellata are members of sedentaria but are motile
Hydrothermal vent ecosystems (white and red worms /Siboglinidae )
- rely on nutrition from chemosynthetic bacteria (does not rely on sunlight at all)
- no stomachs or mouth; digest using bacteria and absorb nutrients with root-like structures
How does sex determination differ among Bonellida viridis?
- Larvae start out with no sex
- Eventually settle on bottom; if they land somewhere suitable to burrow - FEMALE
- If larva falls on a female (lost competition for space) - MALE
What specializations do leeches to eat blood?
- Leeches release special digestive enzymes and some anticoagulants to keep blood from clotting.
- Some also release an anesthetic.
All leeches are parasites. TRUE OR FALSE
false some are carnivores.
What are medicinal leeches used for?
- Release anesthetic and anticoagulent around wound
- Used to reduce blood clotting, relieve pressure from pooling blood, stimulates circulation in reattachment operations for organs with critical blood flow.
What are mollusk synapamorphies?
- Mantle- secretes shell, multiflayered of calcium, salts, and protein.
- Muscular foot
- Gills/Ctenidia - originally used for repiration and switched to combination of respiration and eating, covered in cilia, conveyor belt for gas exchange
- Radula- conveyor belt of teeth used to scrape algae from surfaces
- Complete gut - regional specialization
- Trocophore and veliger larvae ( in most)
What do gills have to do with pre-adaptation?
Gill was a good platform for evolution of feeding.
What is a veliger?
Derived larva found in gastropods and bivalves, has both a shell and a foot. Use a velum to disperese.
What is bad about zebra mussels?
Threaten native freshwater mussels; produce MANY veligers soon in their life; outcompete natives for food and hinder their movement
Rapid formation of many species
Change in allele frequency of a gene due to random sampling; many reduce genetic variation
Loss of genetic variation that occurs when a population is founded by a small group of individuals
Speciation between populations because they are geographically seperated
- Shell-less sea slugs
- Color means posion- mode of defense because shell-less
- Direction of spiral
- Sinistral- left handed
- Dextral- Right handed
- Develops very early and not guided by genes
What is the problem with torsion in snails?
Results in posterior end twisted and ends up over the anterior end. Anus empties near the head.
How does ocean acidification affect mollusks?
Mollusk shells are made of calcium. Acidification increases the solubility of calcium carbonate. This makes building shells hard and shells that are already built dissolve or become soft.
What is metamerization
a linear series of primitively similar segments
Annelids have a closed circulatory system. TRUE OR FALSE
Which taxa have open circulatory systems?
How do metanephridia work?
There is a squiggly thing in every segment that is surrounded by capillaries. Bathed in cappilaries means that wastes can move out of the blood and into the metanephridia. This squiggly thing has an internal opening in the coelom, and an external opening that drains out the excess salt and water.
Having seperate sexes
Major adjustments to Mollusk Ancestoral
- Dorso-ventral axis elongated
- anterior-posterior axis compressed
- Head fused to the foot
- foot modified
- series of prehensile tentacles or arms
- circle of 8 or 10 tentacles surround head
- Often with suckers, some have other structures
- used to capture prey.
Which taxa are most similar to the HAM?
Which taxa have veliger larvae?
Reproduction of Turbellaria
- Sexual- Hemaphrodites, fertilize by copulation
- Asexual- Budding
How do Turbellaria eat?
- Turbellarians are carnivorous. They wrap the body
- around prey, entangling it with mucous.
Reproduction of Monogea
- Direct egg-laying
- Eggs hatch into a ciliated larval stage and disperse
Feeding of Monogea
Reproduction in Trematoda
Sexual and asexual
reproduce sexually (definitive host) and asexually (intermediate host)
What are the two mesozoa groups?
1. Rhombozoa feeding
2. Rhombozoa reproduction
- 1. parasites
- 2. two embryos one asexual
3. Interesting fact
- 1. parasites of marine animals
- 2. fragmentation and sexual
- 3. Causes castration in starfish