Lecture Midterm 1 Flashcards
What are the defining features of eukaryotes?
- Nucleus
- Cytoskeleton
Where did animals come from?
A single-celled ancestor called a choanoflagellate.
What are characteristics of the family Choanoflagellata?
- Heterotrophic •Single flagellum with collar •Suspension feeders •Solitary or colonial •Sister taxon of Metazoa •Choan = funnel (Greek)
Describe Dinoflagellata.
- Usually 2 flagella
- Sulcus: longitudinal groove in which one flagellum lies
- Cingulum: a transverse groove that also has a flagellum
- Theca: rigid cellulose, often sculpted skeleton, occurs in the alveoli
- Auto- and Heterotrophs
- Important primary producers
- Red tides
- Zooxanthellae: Critical for corals•Fish kills
- Bioluminescence
Describe Ciliophora.
- Heterotrophic
- Multiple cilia for locomotion
- Alveolar vesicles
- Mitochondria with tubular cristae
- 2 types of nuclei
- Carbs stored as glycogen
- Cilia
- Somatic and oral ciliature
- Kinetid(cilium w basal body)
- Kinety(row of kinetids)
- Kinetodesma
- (bundling of basal body fibrils)
- Metachronal waves
- Power, recovery strokes
How do Paramecium reproduce?
- Micronucleus– comparable to gonad “master copy”
- Macronucleus- working copies, contains millions of copies of certain genes
- Asexual fission: transverse - fission plane cuts across rows of kinetids
- Sexual conjugation: conjugation -involves meiosis and exchange of haploid micronuclei (macronuclei degenerate prior to conjugation)
What are some advantages of multicellularity?
- Division of labour
- Efficiency (environmental damage & loss)
- Increase in size
- Ecological advantages (predators)
- Metabolic advantages
- Complex tasks
- Information processing
- Biomechanics (speed)
What is the difference between Protozoans and Metazoans?
“Protozoans are eukaryotic, largely unicellular organisms that do not undergo tissue formation through the process of embryological layering.”
“Metazoans are heterotrophic multicellular eukaryotes that undergo embryogenesis by way of tissue layering.”
What are the theories of Metazoan Origin?
Colonial Theory: Metazoa as derived from a colony of flagellated Protozoa, Cell division without separation (currently believed to be correct).
Syncytial Theory: Metazoa as derived from a multi-nucleate but unicellular like a ciliate protozoan, large multinucleate cells that eventually partitioned into compartments, and not much support.
What are apomorphies of Porifera?
Apomorphies
•Microvillar collars surround flagella(choanocytes) arising from single cells or syncytia
•Homologous with choanoflagellates??•Adults sessile and filter feeders, larval stages motile
•Collagen
•Skeletal elements(calcium carbonate and silicondioxide and collagen)
•Aquiferous system
What are apomorphies of Demospongiae
Apomorphies •Spongin-based skeleton (a type of collagen) •Siliceous tetraxons •Spongocytes •Most (>80%) sponges
What are the three general forms of Porifera (sponges)?
Asconoid (thin)
Syconoid (medium)
Leuconoid (large) - all large sponges are leuconoid.
What are apomorphies of Calcarea (Porifera)?
Apomorphies •Calcium carbonate (calcite) spicules •Won’t dissolve in HCL •Large choanocytes •Coeloblastula larva (hollow)
What are apomorphies of Homoscleramorpha (Porifera)?
Apomorphies
•Never with a spongin skeleton;
•Only sponge with basal lamina
•Shallow waters
What are apomorphies of Hexactinellida (glass sponges)
Apomorphies
- Siliceous spicules
- 6-rayed
- Syncytium
- Secondary silicification
Describe Placozoa.
- Discovered in 1883
- Cnidarians? Sponges? Ameboa?
- Phylum of one (?)
- 4-5 cell types & several thousand cells
- Flattened body
- Ciliated upper and lower cells
- Fiber-syncytium (contractile);
- Amoeba-like motion
- Not polarised and can rip itself in two.
- Epithelial cells without basal lamina
What are apomorphies of Cnidaria?
Apomorphies •Stinging cells (cnidocytes) •Polyp adult and planula larva •Nerve nets •Longitudinal and circular muscle •Endodermal gonads •Circular mitochondrial DNA (anthozoans) & linear mtDNA
What is a Cnidae: Nematocyst?
- A secretion of cnidoblast
- For defense (inject toxins)
- For prey capture
What are the cell types of Cnidaria?
Cell Types •Cnidocytes •Muscle •Nerve •Glandular •Interstitial •Ciliated •Sensory •Germ
What are apomorphies of Anthozoa (Cnidaria) ?
- Polyps with pharynx
- Siphonoglyph
- 3 cnidocytes
What are apomorphies of Scyphozoa?
Medusa with:
•Rhopalia(sense organs), which has
- Mesogleal, gastrodermal and epidermal components
- Gastrodermalstatocyst, mechano, photo, and chemoreceptor
•Gastric filaments
•Strobilation
What are apomorphies of Cubozoa?
- Small polyps lacking septa
- Cubic medusa
- Tentacles on pedalia at 4 corners of bell
- Four rhopalia with ocelli
- Velarium – powerful waterjet
What are apomorphies of Hydrozoa?
Apomorphies: •Medusa with velum •Endodermal cnidocytesabsent •Gastrozooids: feeding •Gonosooids: reproductive •Dactylozooids: defense and prey capture
What are apomorphies of Ctenophora?
Biradial symmetry •Diploblastic?? (tri) •Aboral organ •Ciliary rosettes •Photocytes •Ctene rows •Collocytes
What are apomorphies of Bilateria?
Apomorphies •Bilateral symmetry •Mid-sagittal plane (l/r mirror images •Dorsal and ventral sides) •Cephalization •Triploblasts(endo, ecto, mesoderm) •Through gut •Excretory organs
What are the three types of symmetry?
- Radial symmetry: One main axis around which the various body parts are arranged.
- Biradial symmetry: Only two planes can section animal into perfectly similar halves.
- Bilateral symmetry: An axis passes from anterior to posterior. The midsagittal plane separates left from right.
What are apomorphies of Xenocoelomorpha?
Apomorphies
- No anus (lacking through gut)
- Epidermis with uniquecilia
- No discrete organs
- No larval forms
What are apomorphies of Protostomia?
Apomorphies
•Blastopore becomes the mouth
•Schizocoely(schiz = split)
•(coelom (body cavity) is formed by splitting the mesodermal embryonic tissue.)
•triploblastic organisms - three cell layers•ecto-, meso-, endo- derm
What are apomorphies of Spiralia?
Apomorphies
•Larval protonephridia (face outward to the environment)
•Chaetae
•Beta chitin
