BIOL 205 Flashcards
Synapomorphy
Shared derived characters (They appeared in or very shortly before the most recent common ancestor).
Symplesiomorphy
Traits that are shared among members of a clade but are ancestral and much older that the most recent common ancestor. E.g., having four limbs is a symplesiomorphy for mammals.
Homologous vs Convergent characters
Homologous characters are shared characters that were inherited from a common ancestor.
Convergent evolution refers to when a character state evolved independently during different evolutionary events. Not inherited from a common ancestor.
Rank porifera from least complex to most complex.
Asconoid
Syconoid
Leuconoid
Where does water exit a sponge?
The osculum
What are pinacocytes?
Flat “skin cells” of sponges. Line the exterior of the sponge body wall.
What are choanocytes?
Cells that line the interior of sponges that have a central flagellum surrounded by a collar of microvilli.
Function to create the flow of water and capture food items through the sponge.
Make up the choanoderm.
What are the main differences between Calcarea, Hexactinellida and Demospongae?
Calcarea have calcium carbonate spicules and no spongin.
Hexactinellida contain six-rayes siliceous spicules and no spongin.
Demospongia contain spongin and may or may not have siliceous spicules. Will never have 6-rayed spicules.
Sexual reproduction in sponges
Sperm are released into the spongocoel and driven out by the beating of choanocytes. The sperm is then drawn into the aquifer out system of another sponge and engulfed by a choanocyte. The choanocyte then migrates into the mesohyl and carries the sperm to an egg.
What cells are found in the mesohyl?
Amoebocytes and eggs.
As adults what classification would you give most Hexactinellida and Demospongiae?
Leuconoid
Micropyle
Thin region of spongin casing lacking spicules.
Gemmule formation
In autumn archeocytes gather in the mesohyl and undergoes mitosis. A large mass of archeocytes is then surrounded by trophocytes, which are then engulfed by the archeocytes. The archeocytes are then surrounded by a spongin casing. When the parent sponge dies it scatters the gemmules into the sediment which will then hatch when conditions improve in the spring
What forms the lining of the GVC?
Gastrodermis
Which Cnidaria taxa have mesoglea and which have mesenchyne?
What is the difference between the two?
Hydrozoans have mesoglea
Scyphozoans and Anthozoans have mesenchyme.
Mesoglea is a jelly-like matrix that does not contain living cells while mesencyme has living cells.
Which taxa of Cnidaria does not have a medusa stage?
Anthozoa - Sea anemones
In Anthozoa what is the result of sexual reproduction?
The result is a planula larva stage which grows into a new polyp.
In anthozoa, what divides the GVC into smaller chambers?
Thin walls called mesenteries, which are lined with gastrodermis.
Describe the GVC of scyphomedusae.
The GVC has four gastric pouches and the radial canals are extensively branched.
The radial canals connect the pouches to the ring canal.
Describe Scyphomedusae rhopalia
Complex sensory structures which contain statocysts (Sense the orientation of the body relative to the environment), ocelli (photoreceptors) and chemoreceptors.
Each ropallium is located between two flaps called lappets.
Sexual reproduction of Scyphozoa
Occurs during the medusa stage and results in a planula larva. The larva will eventually settle and dormant a tiny polyp known as a scyphistoma.
The scyphistoma then asexually divides in a process called strobilation (strobila stage).
What does strobilation produce? (Scyphozoa)
Young medusae called ephyra.
What life stage is prominent in Hydrozoa?
Hydrozoans have a prominent polyp stage which reproduces asexually and can persist throughout the entire year.
The polyp stage gives rise to an asexually produced medusa stage which reproduces sexually and usually only lives a few months.
Hydrozoan planula larvae
The product of sexual reproduction.
Lecithotrophic - Obtain nutrients from yolk and do not feed.
Gastro vs Gonozooids
Gastrozooids are polyps for feeding
Gonozooids are for the production of gonophores, structures that will develop into medusa.
How does the medusa stage of hydrozoans differ from that of scyphozoans?
Most hydromedusae have a velum, scyphomedusae don’t.
Scyphomedusae have rhopalia as their main sensory structures while hydromedusae have tentacular bulbs.
Scyphomedusa have mesenchyme instead of mesoglea
Scyphomedusae have a more pronounced manubrium with oral arms compared to hydromedusae.
What are the three major types of nematocysts?
Penetrant - barbed base
Volvent (Entangling) - Tightly coiled thread, no barbed base
Glutinant (Adhesive) - Straight thread, no barbed base
What are the taxa of platyhelminthes and are they free living or parasitic?
Polycladida - Free-living
Rhabdocoela - Free-living
Tricladida - Free-living
Neodermata - Parasitic
Platyhelminthes features
Bilateral symettry
Triploblastic
Cephalization
Acoelomate
Monoecious
Coelom
Fluid0filled cavity that is completely enclosed in the body.
In platyhelminthes what produces yolk?
Vitelline glands.
Why are they called Tricaldida?
The GVC has three main branches with many tiny diverticula extending off each of these branches.
How do tricladida eat?
How do tricladida eat?
They extend their pharynx with the GVC opening being at the end of the pharynx.
How do polyclads differ from the other taxa of flatworms?
Their ovaries produce both eggs and yolk.
GVC is extensively branched.
Ruffled pharynx as opposed to cylindrical.
Muller’s larva
Many marine species of polycladida have a larva called muller’s larva.
Other species the young hatch directly from an egg with no larval stage.
What are the two subgroups of the taxon Neodermata?
Trematoda - Flukes
Cestoda - Tapeworms
Epidermis of Neodermata
AS adults they have a highly modified epidermis called the tegument.
The tegument does not have cilia and the cells are fused together.
Cestoda structure
Tapeworms are dorsoventrally flattened parasites.
No GVC, tegument takes on the role of nutrient absorption.
Anterior end has scolex armed with hooks and or suckers used to attach to the intestinal wall.
Proglottids
Contain a set of male and female reproductive organs.
New proglottids formed by budding posterior to the scolex.
Oldest proglottids are the furthest posterior and are gravid (full of eggs).
Cestoda (Taenia solium) life cycle
Gravid proglottids are released from adult tape worm and leave the body of host.
Gravid proglottids break apart releasing eggs
Embryo develops into oncosphere with protective coating and eaten by a pig
Sheds protective coating and burrows through intestinal wall into circulatory system
Once transported to a skeletal muscle develops into invaginated cysticercus.
Infected pork eaten by a human where scolex attaches to intestinal wall.
Mollusc basic characteristics
Complete digestive tract
Ventral muscular foot
Calcareous shell secreted by the mantle
Ctenidia
A mantle cavity
A radula
Visceral mass
Collection of body organs including the reproductive organs and digestive system.
Cerebral ganglia
Mollusc BRAIN
Do molluscs have an open or closed circulatory system?
Open except for cephalopods
Describe the open circulatory system
The ventricle of the heart pumps hemolymph through an aorta then into the hemocoel.
Hemocoel arises from the blastocoel.
Do gastropods undergo torsion? What is torsion?
Yes. Torsion refers to the 180 degree rotation of the visceral mass, mantle and shell relative to the head and foot. This causes the opening of the mantle cavity and the anus to be anterior. Right digestive gland also is smaller han the left.
How would you know a gastropod had detorted?
The anus and mantle cavity would be at the posterior end of the animal but the right digestive gland would remain larger.
Pneumostome
The opening to the mantle cavity in air-breathing gastropods.
OPerculum
Closes the opening to other shell when the whole body is inside.
Where is sperm produced in Helix and where does it go?
Sperm is produced in the ovotestis, passes through the gametic duct before entering the vas deferens.
Spermatophores
Protective casing for sperm. Packaged in the spermatophoric organ before being stored in the vas deferens prior to copulation.
Where are the hormones and mucus used by the love dart produced?
Mucus glands
Where do the spermatophores go after they are received by the vagina?
The copulatory canal.
If the mate has been hit with the love dart they go into the blind deverticulum, if not they are consumed in the bursula copulatrix.
From the blind diverticulum where do the spermatophores go?
The sperm exits the spermatophores.
Copulatort canal -> Oviduct -> Common duct -> Spermathecal sacs within the fertilization chamber of the albumen gland.
Stored there until eggs are ready to be fertilized.
Path of eggs in Helix
Produced in ovotestis (not same time a sperm), once mature pass through the gametic duct and enter the fertilization chamber at the entrance to the albumen gland.
Terrestrial gastropod development
Direct development. Eggs hatch directly into tiny snails.
Scaphopod gas exchange and feeding
Lost ctenidia so exchange gases with the water using the mantle.
Capture microorganisms and organic particles using tentacles (captacula).
Scaphopod reproduction
Dioecious.
]Use external fertilization releasing eggs or sperm into the ocean.
Fertilized egss develop into trochophore larvae then into veliger larvae.
Chiton shells
7 or 8 plates called valves.
Where are ctenidia located in chitons?
In the pallial grooves. Cilia pump water through the grooves to supply water for gas exchange.
Chiton movement and sexuality?
Glide along hard surfaces using waves of muscle contraction of the foot.
Dioecious reproducing using external fertilization. Eggs develop into trochophore larvae then chiton.
Describe the flow of water through an asconoid sponge
Ostium -> spongocoel -> osculum
Which is larger in a sponges mesohyl: eggs or amoebocytes?
Eggs are much larger
Does the polyp stage of hydrozoans reproduce sexually or asexually?
Asexually
Perisarc and coenosarc
Perisarc is a chitinous exoskeleton, the coenosarc is the living tissue inside.
Siphonoglyph
Cilliated grooves within the pharynx
Acontium
Released by anthozoans as a defence mechanism
Contains thousands of glutinant nematocysts
Volvent
Entangling, long coiled thread allowing it to wrap around tiny projections on prey
Glutinant
Long straight thread with a sticky surface for holding onto prey
Rhabdites
Produce mucus
Which mollusc only has a trochophore larval stage?
Polyplacaphora, the other two have a veliger larval stage as well.
