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!)
- Human Importance (sponges)
- First non-food item harvested from the ocean
– Actually became heavily harvested - Pharmaceutical importance
– Cancer-fighting compounds (Forcepia kills lung and breast, Discodermia kills pancreatic) - Industry and technology! (fiberoptics)
Phylum Placozoa
- Branched off from animals early on
- Placo = Flat
- Only one species that we know of: Trichoplax adhaerens (Trich “hair”, Plax “plate”, “adhere”)
Phylum Cnidarian
- Two main body forms (polyp and medusa)
- Unique stinging cells (cnidocytes)
- Jelly layer called mesoglea
- Blind-ended gut with tentacles around mouth
- Asexual and sexual reproduction
- around 10,000 species
- All aquatic (mostly marine)
- 5 main classes
Two body forms (dimorphic)
- Polyp (hydroid) = normally sessile
- “anemone form”
- solitary or colonial forms - Medusa (jelly) = swimming
- “jellyfish form”
Symmetry: Radial (Cnidarians)
- Oral (mouth end) and aboral
- sense environment “from all sides”
– no head
– good for sessile or free-floating animals
Development: Diploblastic (Cnidarians)
- Blastula
- Early Gastrula
- Gastrula
2 sets of true tissues (epidermis, gastrodermis) = diploblastic
Body Structures (Cnidarians)
- Diploblast with 3 “layers”
1. Endoderm (embryo) -> Gastrodermis (adult)
2. Ectoderm (embryo) -> Epidermis (adult)
3. Jelly (nor cellular/non-living) = Mesoglea
Nerve and Muscle Cells (Cnidarians)
- Epitheliomuscular cells
- Nerve cells (one/two-way synapses)
- Nerve net (no “true” brain)
The Cnidocytes (Cnidarians)
- The “nettle animal’s” cell
- Cnidocytes = the cell
(invagination of epithelium) - cnidae = capsules WiTHIN the cell
- most notable cnida is the nematocyst (harpon-like, paralyse prey with venom, stings!)
– cnidocil = hair-like trigger - Rapid - hydrostatic pressure increase
Reproduction (Cnidarians)
Often, alternation of generations
- Asexually-reproducing polyp and sexually-reproducing medusa
- polyp will asexually make medusa
- medusa sexually (meiosis) make gametes
- Gametes fuse to a planula larva
- Planula settles to make new polyp
Polyp Polymorphism
- Mostly in class Hydrozoa
- Clone buds (=zoid) in a single animal (i.e., colony)
- Types of zooid clones:
– Gastrozooids (feeding)
– Gonozooids (reproduction, eggs or sperm)
– Dactylozooids (defence)
Class Anthozoa
- Polyps only - “flower animal”
- 6000+ species
- Anemones, corals
- Tubular body and pharynx, large gastrovascular cavity
Class Anthozoa, Subclass Hexacorallia
- 6 axes of symmetry
- e.g., anemones
- e.g., stony/true/hard corals (mini sea anemones in calcareous cups)
Class Anthozoa, Subclass Octocorallia
- 8-part symmetry
- Georgian corals
– Proteinaceous, fleshy bodies
– Calcareous spicules only in mesoglea “endoskeleton” - Mostly colonial
- e.g., soft corals, sea pansies, sea pens, sea fans
Ecological Importance of Anthozoa
Coral reefs in general!
– Biodiversity hot spots
– Habitats
– 25% of marine life
– Deep sea ecosystems
Photosynthetic dinoflagellates (zooxanthellae)
- Live within the tissues of the coral polyps, microorganisms
- Important for food for coral
- Take in light + CO2, produce sugars and oxygen, coral consumes 90% of sugars
- Coral bleaching, if temp too high, corals will expel the zoos, coral looses color and coral may die if gone for too long
Mutualisms with anemones
- Mucus on fish skin protects from stings
- Crabs
Colorful corals
- Capable of producing proteins that reflect different light frequencies, helpful for zooxanthellae and can reflect UV rays, which could be damaging
Class Staurozoa
- Does not include medusa phase (polyp only)
- 8 extensions (“arms”) with adhesive pads ending in tentacle clusters
- Creeping planula larva (non-swimming)
- Body with white spots with nematocysts to defend gonads
Class Scyphozoa
- True jellies
- 200-400 species
- Small or big!
- Dioecious (separate sexes)
- Large oral lobes extending from mouth
Common Nova Scotia Jellies
- Moon jelly (Aurelia aurita)
- Lion’s Mane Jelly (Cyanea capillata)
Strobilation and Reproduction (Schyphozoa)
- Scyphistoma
- Strobila
- Ephyra
Class Cubozoa
- Square-shaped bells
– tentacles at the corner - Phophalia = eyes
– some eyes are image forming! - Chironex fleckeri (sea wasp)
– fatal
Class Hydrozoa
- Disparate group
- Includes the only freshwater cnidarians (Hydra)
- No medusa
- Can bud off new hydra individuals
- Most are colonial and exhibit polymorphism
- e.g., Obelia
Siphonophores
- Colonial hydrozoans
- bioluminescent
Phylum Platyhelminthes
Flatworms
20,000 dif species
- Acoelomate, bilateral, triploblasts, vermiform
- Most are parasitic
- No anus (most groups), host does digestion
- Flame cells (excretion and osmoregulation)
- Well-developed reproduction
- Most hermaphrodites
- Four classes (“Turbellaria”, Trematoda, monogenea, Cestoda)
- Phylogeny under debate
- Body cavity, but filled with mesoderm tissue
Organisation, symmetry and development of flat worms
- Bilateral and dorso-ventrally flattened
- Triploblastic with acoelomate body plan (parenchyma)
- Organs (eg, ocellus/eyespot)
Flame Cells
- Earliest excretory system
- Filters fluids from inside body
- Removes metabolic wastes
- Controls osmotic pressure
- Retains important ions
- Flame cells + tube cells = protonephridia (first kidneys)
Non parasitic flat worms
Turbellaria: Mecrostomida, Polycladida, Tricladdida
Parasitic flatworms
- Tremotoda: Aspidogatrea, Digenetic flukes
- Monogenea: Monogenetic flukes
- Cestoda: Tapeworms
Class “Turbellaria”
- 4500 species
- Mostly free-living
- Marine, freshwater, (damp) terrestrial
- Can be small to large
- Swim/glide with muscles, cilia, slime
Key features of “Turbellarians”
- Skin and Muscle
- Ciliated epidermis
- Epidermis contains rhabdites
- Attach-and-detach system = dual gland adhesive organs
“Turbellarians” Feeding
- Feeding
- Muscular pharynx in ventral centre of body!
- Intestines can be simple or branches
- Extracellular and intracellular digestion
- Scavengers, predators- Invasive species (Bipalium hammerhead worms)
“Turbellarians” Nervous system
- Nervous system
- Cephalization
- Diffuse nerve plexus and ladder-like pattern
- Auricles:- Ear-like lobes packed with chemoreceptive and tactile cells
- Statocysts (orientation), rheoreceptors (currents) and ocelli (eye spots)
- Ear-like lobes packed with chemoreceptive and tactile cells
“Turbellarians” Reproduction
- Reproduction
- Asexually: fission, regeneration
- Sexually: hermaphrodites, internal fertilization with copulation, can self fertilize
Key features of the Parasitic Classes
- Skin (tegument)
- Syncytial (multi-nucleated), non-ciliated epidermis
- Unites the parasitic group into Neodermata
- Digestive system
- Lacking in some groups (absorption)
- Nervous system
- Minimal cephalization - Reproduction
- Different among classes
Class Trematoda (the parasitic flukes)
- Endoparasitic
- Adaptations for parasitism
- Enzymes, hooks, penetration, cyst forms..
- Over 11, 000 species
- Most have a complex life cycle
- subclass Digenea (two hosts)
Life Cycle of Digenean Flukes
- Intermediate Host = first host, amplification (asexual)
- Definitive Host = Final host (sexual)
Common Digenean Flukes
- Liver flukes
- Undercooked/raw fish
- Blood flukes
- Schistosomiasis
- Directly enters human skin and enter blood vessels and intestines
- Cause anemia and many indirect symptoms and infections
- Swimmer’s Itch
Class Monogenea (one host)
- Ectoparasitic
- On skin/gills of fish
- Opisthaptor attachment
- Simple life cycle
- Eggs -> ciliated larvae -> adult
Class Cestoda
- Tapeworms
- Scolex = NOT THE MOUTH, attaching to host, not for eating
- endoparasitic
- Strobila (main body) and proglottids (reproductive units)
- No digestive system (through skin)
- Microtriches (in skin, how they eat)
Main Body of Cestoda
- NOT true segmentation!
- Reproductive factories!
- Youngest at head, mature (gravid) posterior
- Fertilization from same or different strobila
- Eggs out the uterine pore
How do humans get infected? (Cestoda)
- Fertilized eggs in gravid proglottids
- Protected larvae, out feces
- Cysts in muscles
- Cysticercus gets eaten by definitive host
Phylum Ctenophora
- AKA sea grapes, sea gooseberries, comb jellies
- 8 comb rows with paddle-like ctenes (plates of cilia) for swimming
- Biradial symmetry
- Only have a mouth (oral), same as cnidarians
- Colloblast cells (sticky; AKA “lasso cells”, located on tentacles)
- Exclusively marine
Ctenes
- Ciliary/comb plates (group of cilia) for swimming
- Swim mouth-forward
– waves of beating cilia
Where does the color come from? (ctenophores)
- Most colorless and transparent (near surface)
– Some deep-water species pigmented (e.g. Tortugas red) - Light refraction off ctenes: rainbow
- Bioluminescence
– can emit light (usually at night); phylum with greatest % of luminescents! - Usually blue + green; via proteins in photocyte cells
Ctenophore feeding
- Voracious predators
- Most with 2 retractible tentacles with adhesive colloblasts
- Tentacles wiped across mouth
- Some will use muscular mouth lobes to engulf prey (e.g., beroe)
- Some use cilia on lobes to draw water/prey to mouth (Mnemiopsis)
- no nomatocysts but..
- Haekelia rubra carries undischarged nematocysts after feeding on cnidaria medusa (kleptocnidism)
Body forms (Ctenophores)
- Tentaculate (free swimming)
- Lobate (free swimming)
- Thimble-shaped (free swimming)
- Ribbon (free swimming; Venus Girdle) (largest cilia of animals)
- Creeping sole (epibenthic, sessile)
Nervous System (Ctenophores)
Nerve net similar to Cnidarians
- nerve plexus concentrated under each comb plate
Statocyst
- sense organ on aboral pole (tells up from down)
- with a statolith (calcareous particle)
- Equilibrium
Reproduction (Ctenophores)
Asexual
- Regeneration of virtually any lost part
Sexual
- Most monoecious (hermaphroditic)
- Gametes shed into water via mouth; free swimming larva
- Some undergo internal fertilization and brood their eggs
Bilateria!
- Protostomia and Deuterostomia
- Everything but Ctenophora + cnidaria (radiata), placozoa, porifera
- So good, because cephalization, very effective at getting food, avoiding predators, finding mates, friend or faux, calls (communication)
Bilateria symmetry
- Bilateral symmetry
- Mirrored left and right halves when cut on sagittal plane
- Cephalization!
- Secondary lost in some groups
Cephalization
- Development of sense organs at the anterior end to sense environment head-first
- Moving in one direction
- Forward movement gives an anterior and posterior
- Mouth in head region (anus/wastes in rear, digestion)
Examples of Early Sensory Systems
- Statocyst in Xenacoelomorpha
- Ocelli is planeria (flatworm)
Bilatarian development
- Triploblastic = three embryonic germ layers
- Ectoderm, Endoderm, Mesoderm
- Once you have a mesoderm, true body cavities
Early Bilaterians
- The Acoelomates Xenacoelomorpha and platyhelminthes
Phylum Xenacoelomorpha
- Acoelomates + triploblasts
- In Bilateria, as sister group of Nephrozoa (protostomes + deuterostomes)
- Not connected to any other bilateria
- Neither protostome nor deuterostome
- New phylum!
- Xenoturbella + Acoelomorpha
- Unlike other bilatarians: lack an anus, nephridia (primitive kidneys), and circulatory system
- Simple marine/brackish worms
