Midterm I Flashcards
Animal definition
Multicellular, eukaryotic, heterotrophic, motile, lack of cell walls
Taxonomy
- Formal system to name and group species
- Animals that share more recent common ancestry share more specific features, will be grouped more closely
- More ancient common ancestry: will be placed in different groups, except at higher taxonomic levels
Binomial Nomenclature
- Linnaeus’s system: every species has a Latinized name composed of two different words (binomial) in italics (or underlined)
- First = genus name
- Second = species epithet (generally an adjective, that identifies the species within the genus)
Richness + Abundance
- Richness: How many types of species
- Abundance: how many of each species
Difficulties with measuring biodiversity
- Measuring abundance can be difficult, very abundant organisms, very large area, change with season, life, history motility
- Solution: Only measure richness, or how many species in the area
Participatory science + limitations
- Way of measuring richness, everybody participates
- What is a species? How well has the group been researched? (losing taxonomists, sometimes hard to identify)
- what level are we measuring at (taxonomy)
- Who identifies/verifies what we have found?
- what do we do when ‘species’ is unclear?
- what is the ‘species’ based on?
The Geologic Time Scale
Cenozoic, Mesozoic, Paleozoic, Late Proterozoic
Shared Characters
- Homology: similar character through common ancestry
-Homoplasy: similar character through convergent evolution, not (recently) related
Phyletic groups
- Monophyletic: includes the most recent common ancestor and all of its descendants
- Paraphyletic: A monophyletic group that excludes some of the descendants
- Polyphyletic: A group consisting of members from two non-overlapping monophyletic groups
Animals Architecture
- Levels of organization, complexity
- Body symmetry
- Body cavity organization
- Development traits
- Protostome vs deuterostome - True segmentation
1a. Levels of Organization/complexity
- Protoplasmic level
- All life functions occur within a single cells
- e.g. unicellular eukaryotes
1b. Cellular level
- Aggregation of cells that have differentiated functions
- Adhesion between cells
- E.g., Choanoflagellates (protists - no animals!)
1c. Cell-Tissue level
- Enter, Metazoans (ANIMALS)
- Specific cells work together to have specific functions
- E.g. Porifera, Placozoa
1d. Tissue Level
- True tissues secrete an extracellular matrix (e.g. basement membrane, plasma, collagen)
- Derived from the embryonic germ layer
- Highly coordinated unit
- E.g., nerve net in Cnidarians
1e. Organ and Organ System Levels
- Tissues work together to form an organ with specialized function
- e.g., eyespots in flatworms
- Organ systems (work together, most complex)
- e.g. “digestive system”, “circulatory system”
- Body symmetry
- Bilateral: split down middle, same on both sides (butterfly, person)
- Radial: split a few ways, symmetrical (starfish)
- No symmetry
Cephalization
An evolutionary trend in animals that, over many generations, the special sense organs and nerve ganglia become concentrated towards the rostral end of the body where the mouth is located, often producing an enlarged head
- Body Cavity Organization
Germ Layers
- True body cavities need three embryonic germ layers (triploblastic): endoderm, ectoderm, and mesoderm
- Cnidarians and Ctenophores are Diploblasts so cannot have ANY true body cavity (endoderm and ectoderm only)
- Diploblast gastrulation: division of cells into ectoderm
- Diploblastic vs triploblastic gastrula
- Body cavity Organization
- Space between ectoderm and endoderm
- True Segmentation
Annelids (worms), Arthropods, Chordates
Big (Basal) Splits of Animal Groups
- Porifera (sponges)
- Radiata (Ctenophora and Cnidaria)
- Placozoa
- Bilateria (Protostomia and Deuterostomia)
Groups that descend from Bilateria
- Bilateria, Protostomia, Lophotrochozoa: Larval form: trochophore, same larval form means same ancestor
- Bilateria, Protostomia, Ecdysozoa (means to strip off, all moult)
- Bilateria, Deuterostomia (radial cleavage, regulative embryo, starfish, sea cucumbers, urchins, fishes, primates)
Animals in the water
- Benthic = bottom
- sediments/substrate
- Infaunal (e.g., burrower)
- Epifaunal
- Pelagic = up in water column
- Planktonic
Porifera Chracteristics
- Porifera = Pore-bearing
- Sessile filter-feeders
- Use flagellated “collar cells” (choanocytes) to move water
- Body is an efficient aquatic filter (aquiferous system)
- 5000-8000 spp. of sponges
- Most are marine
- Few live is brackish water
- Around 150 in freshwater
Sponges: Aquiferous System
- Random fact: every 1cm3 of sponge filters 20L of water per day!
- Excurrent pores (OscUla = out)
- Incurrent pores (OstIa = in)
- Spongocoel
Sponges: The Choanocyte
- Flagellated collar cell, move water through the sponge, pick up planktonic food
- Powerhouse!
- Interestingly very similar to the protists Choanoflagellate
- Canal Systems (Sponges)
- Asconoid (AKA choanocyte-lined spongocoel)
- Only in Class Calcarea
- Synocoid (aka choanocyte-lined canals)
- Folded inner layer creates canals
- Also only seen in Class Calcarea
- Leuconoid (aka choanocyte-lined chambers)
- Increase in size
- No spongocoel (just an osculum)
- In all classes
- Main Cells (Sponges)
- Choanocytes
- Water currents and feeding
- Archaeocytes
- Totipotent amoeboid cells in mesophyll
- Can become cells that…
- phagocytosize
- Make spicules
- Make spongin
- Make collagen
- Or are used for reproduction!
- Sponge “skeletons”
- Collagen fibres in all ages
- –some have specific collagen fibres called spongin
- Spicules (calcium carbonate, silica)
– Taxonomic fingerprint!
– Deter predators
- Taxonomy (sponges)
4 classes:
1. Homoscleromorpha
2. Calcarea (calcispongiae)
3. Demospongiae
4. Hexatinellida (hyalospongiae)
Class Homoscleromorpha
- Used to be within Demospongiae
- Spicules non distinct (“same form”)
- Pinacoderm (cellular “skin”) distinct with basal lamina underneath, but only 1 of the 2 types of cell-cell junctions; i.e. incipient epithelium (cell to tissue in between junction)
Class Calcarea
- Calcareous sponges
- The only class with all three canal systems
- Usually small
Class Demospongiae
- 80% of sponges
- Contains the only freshwater sponges!
- All leukonoid
- Commercial bath sponge
Class Hexatinellida (Hyalospongiae)
- 6-rayed silica spicules
– Glass lattice - Syncytial body (external layer, remove membrane junctions between cells, one multinucleated single cell body covering) - Mostly deep sea
Feeding (sponges)
- Intracellular digestion
–phagocytosis
Carnivorous Sponges
- No choanocytes
– Microscopic hook snare unsuspecting prey - Now 137 species (e.g., Harp sponge)
Symbioses (sponges)
- Niches, nesting areas
- Habitats for breeding, feeding, reproduction
- Create clean environments
- Camouflage, a piece of sponge on head
- Take advantage of water coming in, hang out around pores, trap food themselves
- Sponges host good microbes, over 40% of their weight is micro-organisms, photosynthetic so provide the sponge with oxygen
- Reproduction (sponges)
- Both asexual and sexual
- Sexual:
- Sperm from choanocytes
– Released into the water and taken in by another sponge - Oocytes from archaeocytes
Asexual:
- Budding (fragmentation)
- Dormant gemmules (protected internal buds!)