Term
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Definition
| body cavity that arises from the embryonic blastocoel and is not lined by mesoderm tissue |
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Term
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Definition
| splitting of existing mesoderm of embryo |
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Term
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Definition
| invagination of gut, lined by mesoderm |
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Term
| Describe embryonic development of annelids |
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Definition
| are prostomate with true coelom, first organisms with very complex internal organization |
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Term
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Definition
| Bilateral symmetry, paired epidermal chaetae, metamerism |
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Term
| What is the difference between metamerism and tagmatization? |
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Definition
metamerism: segmentation
tagmatization: the specialization of those segments |
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Term
| What are the advantages of metamerism? |
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Definition
1. distinct hydrostatic compartments: locomotion and support
2. reduces impact of injury to region
3. permits tagmatization (specialization) of particular segments to function |
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Term
| How did metamerism develop? |
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Definition
- schizocoely: mesodermal mass splitting to form true coelom
- enlarges in each segment, mesoderm barrier gets progressively thinner between segments
- barrier eventually simplifies to thin septum |
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Term
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Definition
- in annelids
- thin barrier between segments of animal (metamerism) |
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Term
| What type of circulation do annelids have |
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Definition
- closed circulatory system: moves directionally, improved efficiency for transport
- greater pressure in circuit allow for filtration
- pseudohearts: thickened muscular regions in blood vessels |
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Term
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Definition
- multiprotein aggregations in annelid blood
- hemoglobin molecules grouping up together, increasing O2 binding capacity
- other respiratory pigments (red, green) increase the oxygen binding capacity |
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Term
| Protonephridia vs. Metanephridia |
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Definition
- proto: blunt ended tubules w/ flame cells creating currents
- meta: end in open ciliated funnel (nephrostome), higher blood pressure driving fluid into coelom that is processed by metanephridium (also functions for reproduction) |
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Term
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Definition
- evidence of cephalization in annelids
- "brain" in protostomium (head segment) |
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Term
| How are ganglia arranged in annelids? |
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Definition
- segmentally
- collections of nerve bodies controlling movements |
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Term
| When would small/large fibers be used in earthworms? |
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Definition
small: traditional earthworm locomotion and slow movements
large: rapid escape responses |
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Term
| Difference between longitudinal and circular muscle? how do they work together? |
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Definition
- longitudinal: shortens the animal
- circular: extends the animal
- contractions move in wave down body, when one set relaxes other contracts
- setae are buried in tunnel and animal is pulled along |
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Term
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Definition
- parapodial muscles relax on one side: withdrawal of parapodia and setae
- longitudinal muscles fully contract on this side
- on other side: parapodial muscles contract and parapodia extend, longitudinals relax and are stretched out |
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Term
| What will happen if you chop a polychaetes worm in half |
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Definition
| it will regenerate: remarkable ability; although not true reproduction |
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Term
| T or F: earthworms can do transverse fission and budding as asexual means of reproduction |
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Definition
| FALSE. polychaetes can though. |
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Term
| T or F: all annelids can be either dioecious or monoecious |
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Definition
| F: only oligochaetes are monoecious, but all 3 types could be dioecious |
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Term
| distinguish external and internal fertilization |
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Definition
- external: sometimes impressive gamete clouds
- internal: copulation in some species |
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Term
| Do monoecious oligochaetes self? |
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Definition
- not usually
- chances reduced by head to tail arrangement of gonopores |
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Term
| how are eggs released in copulating annelids? |
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Definition
- through gonopore
- through anus
- into coelom, escaping via metanephridium |
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Term
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Definition
| larval stage in many taxa of annelids, a flagellated miniworm that swims around and eventually matures to adult worm [indirect development] |
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Term
| Where are most polychaetes found? |
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Definition
| in marine habitats: floating, benthic, burrowed into ocean floor or beach |
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Term
| What 2 features do oligo's and hirudinea have in common? |
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Definition
- clitellum
- hermaphrodites |
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Term
| T or F: all clitellata have setae |
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Definition
| NO! hirudinea do not have them. |
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Term
| What are some differences in leechs vs. oligos? |
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Definition
- leeches have a more solid body with mismatched segments
- posterior/anterior sucker in leeches
- no setae in leeches |
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Term
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Definition
| common earthworm, subclass oligochaetes, class clitellata, phylum annelida |
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Term
| Ecosystem importance of earthworms |
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Definition
- biologically enriching soil by bringing organics deep
- producing casts = chemical processing of mixed earth
- physical turnover and aeration
- abundance reflects soil quality
- eaten in many countries |
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Term
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Definition
- giant Australian earthworm (1 m long; 2 cm diameter)
- takes up to 5 years to reach reproductive capacity |
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Term
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Definition
| -South African giant earthworm, can be up to 6 m long |
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Term
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Definition
Miniworms
- red colour from respiratory pigment
- breathes through posterior end |
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Term
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Definition
| - hypodermic injection of sperm into mate through spermatophore, sperm make way to ova |
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Term
| What do Hirudinea usually feed on? |
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Definition
- MOST eat small inverts
- but many famous ones are hematophagous (eat blood) |
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Term
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Definition
- leech used historically for bloodletting
- produces anticoagulant (Hirudin) to sustain free blood flow from host |
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Term
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Definition
the Pognophorans
- annelids only seen near deep sea vents
- primarily live in decaying matter in bottom of ocean |
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Term
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Definition
- rely on chemolithotrophic symbiotic bacteria that live in specialized trophosome organ
- allow the tube worms to live in deep sea vents without any sunlight |
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Term
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Definition
| - specialized bag organ in siboglinidae that bacteria live in as chemolithotrophic symbionts, allows to survive without sunlight |
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Term
| Where is the lophophore on molluscs? |
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Definition
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Term
| What are the 4 main classes of mollusc? |
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Definition
| Bivalvia, Gastropoda, Cephalopoda, and Polyplacophora |
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Term
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Definition
main class of mollusc, something that looks like "many plates"
- common name CHITON |
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Term
| What are the synapomorphies of mollusca? |
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Definition
- radula
- muscular foot
- mantle
- reduced coelom |
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Term
| What distinguishes monoplacophora from limpits? |
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Definition
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Term
| How are mollusc coeloms formed? |
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Definition
| schizocoely: splitting of mesoderm |
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Term
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Definition
- secretes calcium carbonate shell
- mantle is layered membrane |
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Term
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Definition
- in all mollusc phyla except bivalves
- scrapes food off substrate, like sandpaper covered tongue |
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Term
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Definition
- expression of sexes separaed in hermaphroditic animal
- male expressed first with testes, when older become females |
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Term
| What does the coelom do in gastropods? |
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Definition
- reduced to point where it is just a small sac of fluid that supports the heart like pericardium
- dont need hydrostatic cavity because locomotion and support is achieved in different ways |
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Term
| snails have what type of circulatory system? |
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Definition
- OPEN
- with 2 chambered heart
- blood freely flows in sinus [less efficient when compared to annelid circulation] |
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Term
| Describe ancestral vs. derived conditions of nephridia in gastropods? What type of nephridium is it? |
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Definition
- ancestral: 2 nephridia
- derived: one nephridium
- not true metanephridium but functionally the same (because of extremely reduced coelom) |
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Term
| Describe differences in marine vs. terrestrial reproduction in gastropods |
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Definition
marine: dioecy and external fertilization
terrestrial: monoecy and internal cross fertilization |
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Term
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Definition
- in gastropods
- respiratory, digestive, and reproductive tracts exit anterior end
- facilitate withdrawal into shell for protection
- cephalization |
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Term
| How do aquatic gastropods respire? |
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Definition
- thin aquatic gastropods breathe across skin, low metabolic rate
- some aquatic snails possess gills within their mantles |
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Term
| How do nudibranches respire? |
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Definition
| - dorsal projections serve as gills/defence (sometimes eat cnidarians and collect nematocysts at tips) |
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Term
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Definition
- in bivalves
- a bag that collects blood on top of pumping ventricles in heart
- 2 auricles + 1 ventricle = bivalve heart |
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Term
| Why are siphons so important for bivalves? |
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Definition
- filter feeding
- respiration |
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Term
| Adductors vs. catch muscles |
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Definition
- adductors: closing quickly
- catch muscles: remaining closed
- energy efficiency |
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Term
| Cephalopod nervous system |
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Definition
- large brains: visual predators
- giant axon: quick escape response
- eyes superficially similar to vertebrate eyes - no blind spot
- cryptic colouration under neuronal control |
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