Flashcards in Lecture Midterm 1 Deck (74):
What are the defining features of eukaryotes?
Where did animals come from?
A single-celled ancestor called a choanoflagellate.
What are characteristics of the family Choanoflagellata?
•Single flagellum with collar
•Solitary or colonial
•Sister taxon of Metazoa
•Choan = funnel (Greek)
•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
•Zooxanthellae: Critical for corals•Fish kills
•Multiple cilia for locomotion
•Mitochondria with tubular cristae
•2 types of nuclei
•Carbs stored as glycogen
•Somatic and oral ciliature
•Kinetid(cilium w basal body)
•Kinety(row of kinetids)
•(bundling of basal body fibrils)
•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)
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?
•Microvillar collars surround flagella(choanocytes) arising from single cells or syncytia
•Homologous with choanoflagellates??•Adults sessile and filter feeders, larval stages motile
•Skeletal elements(calcium carbonate and silicondioxide and collagen)
What are apomorphies of Demospongiae
•Spongin-based skeleton (a type of collagen)
•Most (>80%) sponges
What are the three general forms of Porifera (sponges)?
Leuconoid (large) - all large sponges are leuconoid.
What are apomorphies of Calcarea (Porifera)?
•Calcium carbonate (calcite) spicules
•Won’t dissolve in HCL
•Coeloblastula larva (hollow)
What are apomorphies of Homoscleramorpha (Porifera)?
•Never with a spongin skeleton;
•Only sponge with basal lamina
What are apomorphies of Hexactinellida (glass sponges)
- Siliceous spicules
- Secondary silicification
•Discovered in 1883
•Cnidarians? Sponges? Ameboa?
•Phylum of one (?)
•4-5 cell types & several thousand cells
•Ciliated upper and lower cells
•Not polarised and can rip itself in two.
•Epithelial cells without basal lamina
What are apomorphies of Cnidaria?
•Stinging cells (cnidocytes)
•Polyp adult and planula larva
•Longitudinal and circular muscle
•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?
What are apomorphies of Anthozoa (Cnidaria) ?
•Polyps with pharynx
What are apomorphies of Scyphozoa?
•Rhopalia(sense organs), which has
- Mesogleal, gastrodermal and epidermal components
- Gastrodermalstatocyst, mechano, photo, and chemoreceptor
What are apomorphies of Cubozoa?
•Small polyps lacking septa
•Tentacles on pedalia at 4 corners of bell
•Four rhopalia with ocelli
•Velarium – powerful waterjet
What are apomorphies of Hydrozoa?
•Medusa with velum
•Dactylozooids: defense and prey capture
What are apomorphies of Ctenophora?
What are apomorphies of Bilateria?
•Mid-sagittal plane (l/r mirror images
•Dorsal and ventral sides)
•Triploblasts(endo, ecto, mesoderm)
What are the three types of symmetry?
1. Radial symmetry: One main axis around which the various body parts are arranged.
2. Biradial symmetry: Only two planes can section animal into perfectly similar halves.
3. Bilateral symmetry: An axis passes from anterior to posterior. The midsagittal plane separates left from right.
What are apomorphies of Xenocoelomorpha?
- No anus (lacking through gut)
- Epidermis with uniquecilia
- No discrete organs
- No larval forms
What are apomorphies of Protostomia?
•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?
•Larval protonephridia (face outward to the environment)
What is included in Protostomia?
•Spiralia: Annelids, mollusks, Bryozoans, Chaetognaths, Rotifers etc.
•Ecdysozoa: Moulting animals – arthropods, Nematodes
What are apomorphies of Platyhelminthes?
•Multi-ciliated epidermis and gastrodermis
•Two cilia per protonephridial terminal cell
Describe the musculature of Platyhelimthes?
•Muscular waves - swimming
What are Neoblasts?
- Adult stem cells.
•Pluripotent: ability to differentiate into all zygotic cell types.
•Likely even totipotent (differentiation into all zygotic cell types + extraembryonic tissues)
Describe the digestive system of Platyhelminthes.
•Mouth, no anus
•Phagocytic, gland cells
What are apomorphies of Neodermata?
•Neodermis(or tegument): adaptation to parasiticlife style
•Protection from gut enzymes, absorption of nutrients from host
What are apomorphies Neodermata, Trematoda?
•Flatworms or flukes,
•Larval epidermis is combination of ciliated cells and syncytial neodermis.
•Two or more hosts
•Molluscs are the primary hosts.
•Huge health problem for humans
What are apomorphies of Aspidogastrea (Trematoda)?
•Large, complex ventral adult sucker.
•Aspido = shield
•Mostly fish and turtles
What are apomorphies of Digenea (flukes)?
•Miracidium larva with transverse bands of ciliated cells.
•Intermediate (mollusc) and definitive (vert) hosts.
Describe the Digenean life cycle.
•1st intermediate host ‐ snail
•2nd intermediate host (if present) ‐arthropod or fish
•Definitive host is a vertebrate
•Definitive host = one in which the parasite reaches maturity and reproduces sexually
What are apomorphies of Cestoda (tapeworms)?
•Ciliated larval epidermis syncytial
What are apomorphies of Rotifera?
•Ciliary corona on head
- “Wheel organ” = rota = L for wheel•Unpaired retrocerebral gland
•Secretes mucus to lubricate wheel•Female has vitellarium
- Syncytial structure produces eggs
What are apomorphies of Chaetognatha (arrow worms)?
- Alpha-chitin, hollow,
- Capture prey, envenomate
- Encapsulated in a hood
•Ciliary fences (corona ciliata)
- sensing prey
•Double-walled lateral fins
- Chitinous cuticle occurs at the head
- Along rest of the ‘torpedo’ 3-5 layers thick
What are the parts of the Lophophorate body?
•Mesosome: coelomcontaining, lophophore
•Metasome: most of the body
•Zooecium: exoskeleton secreted by the metasome
What are apomorphies of Lophophores?
•Introvert: The anterior part of the body forms an introvert, within which the lophophore and tentacles can be withdrawn
- A cilliated groove in the mesothelium along which eggs move to be released to the environment
•In some groups –eurystomes
•Autozooids– feeding zooids
•Avicularia–jaw-like mechanism used for defense
•Vibracula-large cilia-like structure use to keep colony clean, sometimes for locomotion
What are the types of Bryozoan colonies?
- Stolonate: hydroid shaped
- Foliaceous – leaf-like
- Encrusting (Most common)
What are characteristics of Brachiopoda?
•Lampshells (similarity to Romanoillamps)
•Marine benthic suspension feeders
•Live attached to rocks
•5+cm in size (large)
•~350 species today
•superficial resemblance to bivalves
What is the difference between Bivalve Molluscs and Brachiopods?
•Valves are lateral (left and right)
•Valves are dorsal and ventral
What are apomorphies of Brachiopoda?
•Bivalve shell & mantle
- Calcareous lophophore support
•Heart is dorsal
•Adductor muscle contraction pulls valves together and closes shell
•Abductor (diductor) muscles. Contraction opens the valves
•Pedicle(extension of the body wall) connects to the substrate
Describe Brachiopod morphology.
•valves are dorsal and ventral in brachiopods
•Inarticulata and Articulata
•presence or absence of hinge teeth and sockets
•most modern brachiopods are Articulata
•hinge that holds two valves together is more developed in Articulata
•Shell secreted by outer mantle edge (outgrowth of body wall)
•Pedicle: attachment stalk (symmetry)
What are apomorphies of Phoronida?
•Corpuscular hemoglobin in hemalsystem
•An adaptation to life in anoxic or hypoxic conditions
- Lophophore extends up into the oxygenated water, but this water is not circulated to the remainder of the organism in the tube
Describe Phoronid morphology.
•Secretchitinous tubes - sediment particles are incorporated into the tube
•Never leave tube - closed posterior
•Swollen posterior ampulla
•Coelom creates hydrostatic skeleton
•Muscle fibers allow movement inside tube
•Feeding: Use upstream collection system
•Lophophore can be autotomised
What are apomorphies of Annelida (Little Ring)?
- Metamerism (segmentation)
•Septa divides fluid filled coelom
•Added sequentially (youngest is??)
•Echiura’s apparentlyun‐segmented body infact represents a series of fused segments
What is Metamerism?
Structural plan in which the body is differentiated along its longitudinal axis into a series of units or segments, each containing elements of the chief systems of organs.
What are the three body regions of Annelids?
What do Metameres (of Annelids) contain?
•Pair of mesodermal somites with coelomic spaces
•Pair of nephridia (excretion)
•Pair of coelomoducts (ciliated excretory and reproductive channels)
•Pair of ganglia on a ventral nerve cord•Pair of appendages
What is the difference between Segmentation and Metamerism?
- Derived from the Ectoderm.
- Confined to only the ectoderm.
- Derived from the Mesoderm.
- Confined to ectoderm and mesoderm (not endoderm).
What are advantages of Metamerism?
•Build a large organism from a simple plan
•Effective servicing of major systems
•Enables flexible and/or complex movements•Loss of parts not fatal
•Opportunities for specialization
What is Tagmatization?
Metameres are grouped sometimes into tagmata. Tagmata are structurally differentiated groups of segments specialized to perform specific functions for the whole organism. Some polychaetes, but reaches greatest extent in Arthropoda (head, thorax, abdomen).
What are apomorphies of Errantia "Polychaeta"?
•Parapodia: each of a number of paired muscular bristle-bearing appendages used in locomotion, sensation, or respiration.
•Nuchal organs: chemoreception ciliated pit or grove, light detection, food detection.
•Pedal ganglia: control parapodial movements.
•Pair of pygidial cirri: sensory appendage.
What are the three major lifestyles of Errantia "Polychaeta"?
What are apomorphies of Sedentaria; Clitellata?
•Clitellum: series of anterior segments enclosed in thick, glandular epidermis – girdle –reproductive structure
What are apomorphies of Hirudinomorpha?
•Dorsal anus anterior to sucker
•Superficial annulations: un‐segmented body with superficial marks
•Unpaired mid‐ventral gonopore
•Ectoparasitic: lives on surface of host
•Sensory papillae: specialised sense organs ‐small projecting discs in a ring around one annulation.
What are apomorphies of Echiura?
•Pair of anterior ventral chaetae
•2 posterior rings of chaetae (beta-chitin)
•Used for digging
•Echiura’s apparently un-segmented body in fact represents a series of fused segments
•Prostomial and trunk coeloms (like sipunculans)
•Intestinal siphon (accessory gut – water bypasses the main gut)
What are apomorphies of Sipuncula (peanut worms)?
•Eversible (circular muscles)
•Introvert retractor muscles
•Te n t a c l e s
•J-shaped intestinal tract
•Intestinal ciliary groove (water shunt)
•Cuticle with scattered hooks
•Hemerythrin in cells
What are apomorphies of Mollusca?
•Dorsal mantle with secreted chitin cuticle and calcareous spicules
•Foot and paired pedal retractor muscles
•Tetraneural nervous system
•pair pedal nerve cords
•pair of visceral nerve cords
What are apomorphies of Aplacophora?
•Cylindrical vermiform body
•Mantle with cuticle and spicules
•Solenogastres: live on branches of cnidarians
•Caudofoveata: burrowing in sediment
What are apomorphies Eumollusca?
•Complex radular musculature
•Odontophore with chondroidsupports
What are apomorphies of Polyplacophora?
•GR poly-(many), plako-(tablet), and -phoros(bearing)•8 dorsal overlapping valves
•Valves have tegmentum and articulamentum layers
•sense organs embedded in the tegmentum of each valve
Describe the morphology of molluscs.
•Enrollment muscles: longitudinal - can roll self into a ball
•Inhalant and exhalant aperture are anterior and posterior, respectively
What are apomorphies of
•One piece shell with periostracum and calcareous layers
•Mantle margins with 3 folds
•stiff mass in stomach and style sack of digestive enzymes
•Mantle spicules absent
•8 pairs of dorsoventral pedal retractor muscle
What are apomorphies of Gastropoda?
•To r s i o n
•Usually coiled, asymmetrical
•Anterior mantle cavity
•Left gonad lost
What are the parts of a snail shell?
•Periostracum: proteinaceousouter layer
•Ostracum: prismatic layer -bricks are perpendicular to surface
•Hypostracum: plywood-like •Nacreous layer: mother of pearl