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?
What are characteristics of ALL the classes in platyhelminthes?
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
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)
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
~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.
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
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
How do Turbellaria eat?
Turbellarians are carnivorous. They wrap the body
around prey, entangling it with mucous.
Reproduction of Monogea
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)