Bio Exam 3 First 4 Lectures
What does the word gnathostome mean?
"Jaw Mouth"
What is a placoderm? "Plate Skin"
- In fossil record from Silurian (~440 MYA) to Devonian (~360 MYA) - Represented by 200 described genera!! - Heavily armored head region (lots of dermal bone) - With jaws, but LACKING teeth (*implies "jaws first" evolution in gnathostomes)
Why is their colonial nature important phylogenetically?
-Often live as colonies- show some cellular specialization- "animal like"
Why is the shape of their cells important phylogenetically?
-cells are very similar to collar-cells (choanocytes) of sponges
What characteristics unite and describe animals?
-multicellular -heterotrophic eukaryotes that ingest food items -with tissues that develop from embryonic germ layers
There are a large number of terrestrial, lungless salamanders. Why are there no lungless lizards?
-salamanders can breath through their skin(can't remember word for it will update when slides are posted), lizards cannot
What is the most successful clade of Lepidosaurs? What unique adaptations have helped them?
-snakes are most successful "Lizards" -Jaw morphology allows them to eat large prey • Dietary specialization • Venom also an important innovation o Venom:toxin delivered via fangs
What are the "local" and "global" threats to coral reefs?
1) "Local" threats • Land-based pollution (chemicals & sedimentation), mining and "blast" fishing 2) Waters too warm • Photosynthetic dinoflagellates are expelled, corals "bleach" 3) Declining ocean pH associated with increased atmospheric CO2 • Calcification (corals + others) decreases as oceans become more acidic
Arthropods are the most successful animal group - what are some reasons we can say that?
1) Ecological Diversity - in essentially all habitats >> aquatic + dominant life form on land & in the air 2) Numerically Dominant Metazoans - some estimates suggest a billion, billion individuals 3) Species Diversity - 2/3rd of all described animals; ~1 million species described
What are the primary differences between Deuterostomes vs Protostomes? - remember the Table of differences.
1) Position of Nervous System -Ventral for Protostomes and Dorsal for Deuterostomes 2) Gene Duplication in HOX Gene Family -No duplication for protostomes, duplication of posterior HOX genes in deuterstomes 3) Fate of Blastopore (= first opening of future gut during embryonic development*)
Cephalopods are intelligent animals - give three examples of such intelligence.
1) Use tools for defense 2) Can solve problems 3) Show long-term memory 4) Can recognize individual conspecifics 5) Can recognize human caretakers •6) Complex social communication
Three genomic processes have resulted in the HOX gene differences observed between Protostomes and Deuterostomes - what are these processes?
1.) Duplication of genes on a single chromosome => results in "family" of related genes ("gene birth") 2.) Two-fold Whole genome duplication in early-diverging deuterostomes 3.) Some genes lose functionality because of functional redundancy ("gene death")
What are the 4 stages of complete metamorphosis? Why is a different larval stage an advantage?
Advantage: Don't have to compete for food
Cephalopods have a camera-lens type eye. This type of eye is said to have evolved convergently in cephalopods and vertebrates - what does this mean??
Camera-lens Eye in some Cephalopods - functionally very similar to vertebrate eye, evolved independently (example of convergent evolution)
Why are sea squirts (tunicates) strange chordates?
Chordate characteristics seen in larval stage
What are the 5 keys to insect success as a group? Understand each one
I) Complex senses of vision, hearing, olfaction, touch, etc.. •Pollination (finding flowers), sexual interactions (finding conspecific mates), parasitism (finding hosts) => all require complex sensory systems 2) Possess wings (only invert animals with wings) •Insects first animals to evolve ability to fly •restricted to adult insects •NOT appendages - cuticular extensions of dorsal thorax => unlike flying vertebrates, do NOT forfeit functionality of appendages to fly!!! •Most (not all) adult insects with 2 pairs of wings (on middle & hind segments of thorax) •Fore-wing (Mesothorax) •Hind-wing (Metathorax) •Best fliers actually only use a single functional pair of wings •Of course, flight is advantageous: • escaping predators • colonizing new regions, habitats • move efficiently to patchy resources (e.g., water sources, other animals, plants, flowers) 3) co-Diversification with plants (e.g., pollination, plant-feeding) •Pollination is (usually) a +/+ ecological interaction •Mutualism - both parties benefit, evolve codependence •Plants receive fertilization services, insects rewarded with nutrient-rich nectars & pollen 4) Most diverse groups (but NOT all insects) with Complete Metamorphosis: Egg >> larva >> pupa >> adult stages •Some, but not all insects, have Complete Metamorphosis •involves a major morphological change during development (larvae vs. pupae vs. adult) •Two implications of Complete Metamorphosis: • I) Major morphological change implies major ecological difference between life stages (= reduced competition among life stages) • II) Pupal stage can evade harsh seasonal conditions, populations can rapidly respond to resource availability • The "Big 4" ALL exhibit complete metamorphosis - again, partly responsible for success of these groups 5) Many are Parasites •Many Insects are Parasites (Using other animals as food resource) •Many insects are parasites of other insects • e.g., huge diversity of LEPIDOPTERAN larvae (caterpillars) • These caterpillars comprise large resource for parasitic wasps
Tetrapods ultimately evolved to be land animals. What characters already possessed by tetrapod ancestors facilitated this transition to land?
I. Bony Endoskeleton a. system of body support in a non-supportive environment II. Lungs (*gills don't work on land!) . primitive feature for Bony-fishes (Osteichthyes) III. Pectoral & pelvic girdles, with associated limbs + terminal phalanges => . obviously important in land-based locomotion
What are key structural proteins in the amniote integument? Give three examples of epidermal structures that are mostly comprised of these key proteins. How do these structures further facilitate life on land?
Keratins: they replace all/most metabolically active cytoplasm -Karatinized cells are resistant to abrasion and water loss 1. Skin covering 2. Mammal hair 3. Hair derivatives (claws, hooves) 4. Scales 5. Feathers
What are some insect ectoparasites that humans deal with?
Lice and Fleas
Remember what major group do water bears belong in?
Protostomia -> Ecdysozoa -> Panarthropoda -> Tardigrades
What are the two keys for spider success?
Silks and Venoms
Amphibians are either "tied to water" (i.e., must have water to complete part of their lifecycle), or found in moist terrestrial habitats. What aspects of amphibian biology impose these constraints?
Skin is permeable to respiratory gases (many taxa with cutaneous respiration) -thin, permeable skin implies dessication in dry habitats -eggs covered with a jelly-like substance, no protective shell, need to be in a pond or river
The -optera/ptera ending in insect orders refers to what?
Wing
About how many times has a snake-like form evolved from a limbed ancestor within living Lepidosaurs? What features can you generally use to determine a true snake from a legless lizard?
twice, in snakes and legless lizards -legless lizards often have eyelids and/or ear opening
Be able to describe the mimicry seen with coral snakes
• -Batesian mimicry: harmless species evolve coloration/pattern/behavior that mimics the harmful species (model) • -many harmless species have evolved coloration/pattern that mimics that of coral snakes • -mimicry is common in north and south americas
Why is Tiktaalik an important fossil tetrapod - i.e., what does this fossil tell us about tetrapod evolution?
• It's a fish with wrists
How are animals related to other multicellular eukaryotes? (3 Ways)
• Membrane bound nucleus • Membrane bound organelles • Linear DNA
There are multiple causes for amphibian population crashes and species extinctions - what are these? One cause is particularly problematic - what is this problem? Remember that we talked about it previously.
•"Standard" problems: o 1. Habitat destruction 2. Over-exploitation •Other Factors: o 1. Introduced species (e.g., mountain yellow-legged frogs impacted by introduced trout in CA) 2. Climate change, including increased UV-B radiation 3. Water pollutants o Very Problematic!!! 4. Emerging infectious diseases => chytrid fungus
Define parasitism. Your friend tells you that parasites are lowly animals, barely evolved. You respond, "nope", parasites are actually very successful, for the following reasons .......
•+/- ecological interaction => Parasites benefit at expense of host, typically NOT killing host as single individuals •Parasites live inside (endoparasites), or attached to outer surface (ectoparasites) of animal host body, obtain nutrients from host •Parasites are NOT 'degenerate' animals, but rather, highly-specialized for a unique lifestyle •Basically, ALL animals serve as hosts for one or more parasites - yes, this includes humans -Why do we consider Animal Parasites Successful? • 1) Essentially all animal groups include some parasitic representatives (lifestyle has evolved many times independently from nonparasitic ancestry) • 2) Perhaps 1/2?? of all animal species are parasites!! (numbers skewed by mega-diverse groups, e.g., nematodes, parasitic wasps, etc..)
Name 4 major anatomical changes that occur in the transition from tadpole to adult frog?
•1) loss of gills, 2) formation of limbs, 3) loss of tail, 4) change of digestive system
What is the triploblastic condition? What are the ultimate developmental fates of the three individual triploblastic germ cell layers in Bilaterians?
•3 EGCLs = endoderm, ectoderm, mesoderm; these germ layers develop into specific adult tissues/organs: •ectoderm - outer body covering, nervous system •endoderm - gut lining, liver, lungs -mesoderm - true muscle tissue, bone, connective tissues, etc.
What is the basic body plan of an insect?
•3-part body plan as adults => head, thorax, & abdomen •3 pairs of legs arising from thorax (= hexapod)
When did tetrapod terrestrial invasions occur? Were tetrapods the first animals onto land?
•360-380 MYA •Plants/other animals already on land
Genes are often duplicated in genomes (i.e., a single gene gives rises to two "daughter" genes through duplication of a chromosome or part of a chromosome). What are the three possible fates of such duplicated genes?
•A) Lose functionality (pseudogene), go "extinct" B) Neofunctionalization - evolve a "new function" different from ancestral gene C) Subfunctionalization - two "daughter" genes each take on part of function of "mother" gene
What are the two primary groups of living tetrapods? (Tetrapoda=4 limbed vertebrates)
•Amphibians •Amniotes (Reptiles, Birds, and Mammals)
Discuss the colonial body organization of Physalia.
•An individual is actually a colonial animal made of physiologically-connected 2N zooids/individual animals, all derived from a single zooid via budding
Where did the animal kingdom originate? Why might this be important?
•Animal Life began in Oceans •The majority of the major animal groups remain marine •A handful of animal clades have invaded Land, 2 groups are particularly successful on Land => (Arthropods and Vertebrates) •Some have returned back to oceans
What do both confirm, however?
•Animals have a very DEEP history on Earth
What is the ECM and why is it important?
•Animals have extracellular matrix (ECM) while plants have Cells walls, •Primary components include glycoproteins (most important = collagen) and proteoglycans (small protein core + linked carbohydrate chains) •Holds cells together in tissues, adds structural support, acts as a filter, involved in cell communication -Cell communication & coordination very important in multicellular organisms
Besides earthworms, what organisms are in Annelida? Where is much of the diversity found?
•Annelida = "little rings" Segmented worms include marine, freshwater and terrestrial species •Errantians (errant = traveling) are marine group. Include mobile predators, algae grazers and large tube-dwellers. Some have parapodia on each segment that aid in locomotion •Sedentarians (sedere = to sit) burrowers and tube-dwellers • Christmas tree worm has elaborate gills - gas exchange and feeding
When was the Cambrian explosion, and why is it of interest?
•Around 530 MYA •Major Point of Diversification •Fossils representing around half of extant Animal groups appear suddenly •Much diversification over a very short geologic time span •Most fossils from cambrian expl are Bilaterian
About when did arthropods invade land?
•Arthropods = first animals to invade land, ~ 420 MYA
What does the cuticle help form in arthropods?
•Arthropods Only - chitinous cuticle functions as external skeleton (= exoskeleton)
What is a "body plan"?
•Body Plan = a description of the overall system of body organization •important features: symmetry, tissue complexity, with or w/out appendages, segmentation
How do lungfish breathe? When during vertebrate evolution did lungs evolve (i.e., at the base of which clade, where on the vertebrate tree)? Through their skin
•Both Gill & Lung Respiration
Ctenophore/comb jellies: how are they similar to jellyfish? How are they different?
•Both are transparent, mostly water, and carnivores •Different in that comb jellies have: • Two openings (mouth and anus) • Medusa with eight "combs" of cilia - move • Planktonic predators, acquire prey w/ sticky threads
What are two primary features that suggest a relatively early phylogenetic divergence for Sponges?
•Cellular Grade of Organization (GoO) • LACK true embryological germ cell layers • LACK adult tissue layers (contrasts with TISSUE GoO all other animals) •More cell individuality than typical cells in remaining animals • Some cells mobile • Cell differentiation is reversible (amoebocytes in particular)
What are the four main groups of living arthropods?
•Chelicerata •Crustacea •Myriapoda •Hexapoda
What is the closest single-celled relative of animals? What do they look like?
•Choanoflagellates -small, aquatic flagellates
What are the big four insect orders?
•Coleoptera (beetles) •Lepidoptera (moths, butterflies) •Hymenoptera (bees, wasps, ants) •Diptera (true flies)
What are conotoxins? How has conotoxin diversity evolved?
•Cone Snails (Conus) - marine gastropods •Diverse, mostly tropical genus (~ 700 species) -Predators, feeding on worms, other snails, fish •Radula modified as venom-delivering 'harpoon", potential speeds of 200 m/sec!! •Cone Snail Toxins (Conotoxins) •Peptides (small 10-40 AA proteins) isolated from Conus •Any single species produces a "venom cocktail" including many small peptides (up to 200 different peptide molecules) •Each conotoxin is targeted to very specific cell receptor targets (mostly ion channels) •Different genes (peptides) in same "gene family" = evolved via gene duplication, allowing evolution of new peptide functions!!
Why are crustaceans so important in marine environments?
•Copepods - planktonic among most numerous of all animals •Algae grazers •Shrimp-like krill also abundant
What are coral reefs? Why are coral reefs both economically & ecologically valuable - at least 3 reasons?
•Coral Reefs, reef building corals (colonial Anthozoans) with calcium carbonate skeletons formed from symbiosis with photosynthetic dinoflagellates. •Structural Complexity a KEY reason for diversity •Corals - some hydrozoans, mostly anthozoans •Econ/Ecol valuable: 1.) Hold high diversity of organisms 2.) Extremely rich biologically ("Rainforests of the Sea") 3.) A lot of different niches in a coral reef 4.) Support a number of human economic activities
How do choanocytes work, and how are these cells fundamental to the sponge design? What role do choanocytes play in sponge reproduction?
•Create water currents and trap microscopic food particles/gametes; also involved in egg & sperm production •Choanocytes give up sperm to the egg
Do the cuticles of nematodes act as an "exoskeleton"?
•Cuticular integument NOT acting as external skeleton (hydroskeleton)
Define diploblastic. What are the two embryonic germ cell layers in diploblasts, and which tissue layers do these give rise to in Cnidaria?
•Diploblastic: two EGCLs (ectoderm and endoderm) which give rise to specific adult tissues: • Endoderm => forms adult gastrodermis • Ectoderm => forms adult epidermis
What morphological feature unites the clade Ecdysozoa?
•Ecdysozoans = "molting animals" - protein-based outer body covering (cuticle) that is periodically molted for growth (= Ecdysis) •Several groups with worm-like body plans (e.g., nematode worms, kinorhynchs, nematomorphs, etc.) •Lack appendages, mostly marine, fluid-based skeleton
The ray-finned fish epidermis has multiple functions - what are these??
•Epidermal glands secrete " mucous " o Reduces drag; provides protection from pathogens; o Nearly "watertight" - barrier to water gain/loss
Did gnathostome lungs evolve on land, or in aquatic habitats? What is the evolutionary fate of lungs in some Ray-finned fishes? How do these animals thus respire?
•First evolved in fishes •Initially evolved as evaginations of the pharyngeal region of the digestive tract
Why are fossils and molecular clocks in disagreement over the age of animals?
•Fossil records are incomplete and Molecular clocks (which are calculated through genes + phylogeny + fossil calibrations) may not be accurate models
Recall the four key chordate characters. These characters evolve into different structures with different functions in derived chordates - give an example using the pharyngeal gill slits.
•Four key chordate characters 1.) Dorsal, hollow nerve cord 2.) Notochord Fibrous, supportive rod extending length of body beneath dorsal nerve cord 3.) Pharyngeal slits or clefts • Allow water to bypass digestive tract • Suspension-feeding devices in invertebrate chordates 4.) Muscular, post-anal tail
Summarize the species and ecological diversity of molluscs. What are the 3 major groups of molluscs, with examples of each?
•Gastropoda (Snails, slugs) •Bivalvia (clams, mussels, scallops, oysters) •Cephalopoda (squids, octopuses, cuttlefishes)
What is the function of the gastrovascular cavity (GV cavity) in Cnidarians? How does this function relate to basic cellular requirements (i.e., nutrition, respiration, etc)?
•Gastrovascular Cavity extends throughout body • functions as simple transport system for exchange of food items, gases, wastes •Single oral opening leads to blind gut => Gastrovascular Cavity •GV cavity sometimes greatly subdivided (e.g., extends into tentacles) •All cells of body in contact with GV fluids or external medium
Explain how the countercurrent exchange mechanism allows fish to extract oxygen from the water as it flows over their gills.
•Gills protected by a bony operculum •Used alone, or in combination with lungs
Vertebrates are said to be morphologically disparate - what does this mean?
•Great variation in morphological form despite relatively limited species diversity •As an example, contrast this with beetles => HUGE number of species, limited diversity in form
What are HOX genes, and why are they important to animals?
•HOX genes => highly conserved developmental regulatory genes •Possessed by all metazoans •Control body plan/regulate body formation during development •Unique to animals
Describe the amniote egg, including functions of the four extraembryonic membranes. Why does the amniote egg further facilitate life on land?
•Has 4 extraembryonic membranes, 3 unique to Amniotes o Amnion: Surrounds embryo in fluid- filled cavity; cushioning & preventing dehydration o Allantois: Extends from hind gut; Storage of metabolic waste products, aids in gas exchange o Chorion: Outer-most membrane; involved in gas exchange o Yolk Sac: includes yolk, providing nutrients
What is the role of cadherin?
•Important in cell-cell adhesion => key to evolution of multicellularity
Where are most crustacean species found?
•Includes crabs, lobsters, shrimp, woodlice, and more 67,000 described species •Most are marine (freshwater, terrestrial)
What's so interesting about comb jellies pooping?
•It does not come out of their mouth, which allows them to be more complex and to eat while digesting
Why are gnathostomes successful?
•Jaws (& Teeth) - grasp, manipulate, shear food objects => New food resources become available Unpaired + paired fins => better, faster, more maneuverable swimmers
Jaws evolved from which structures in more early-diverging Vertebrates? What is the evidence for this homology?
•Jaws evolved from anterior pharyngeal arches of early-diverging vertebrates •Evidence for Gill Rod - Jaw Homology 1) Position on body (positional homology) 2) Both structures derived during development from neural crest cells 3) Nerve distribution to associated muscles is similar
Which of the big four has many parasitic species whose hosts are other arthropods?
•LEPIDOPTERAN larvae (caterpillars) comprise large resource for parasitic wasps
What are some well-known parasitic annelids?
•Leeches - mostly freshwater (a few marine, a few terrestrial) Invertebrate predators and blood suckers (Release and anesthetic and anticoagulant)
Why are modern coelocanths considered "living fossils"? What are general characteristics of "living fossils"?
•Living FOssil: A living (extant) species representing a group that was previously more diverse, and has a well-known fossil record (e.g., sturgeon) o Typically exhibit slow rates of morphological evolution living species surprisingly similar in morphology to fossil species
Why can't shark populations quickly rebound after over-harvesting - at least three reasons?
•Long Age to maturity •Small Litter size •Biennial reproductive frequency •Gestation period of 9-24 months
Why is pollination such a valuable ecosystem service?
•Majority of flowering plants depend upon insects for pollination •=> essentially all terrestrial ecosystems would collapse without this interaction; this includes Agroecosystems •One of the most important Ecosystem Services on Earth
What are some of the specialized appendages found in crustaceans?
•Many specialized appendages: antennae, mouthparts, walking legs, feeding legs, swimming legs
Why are silk proteins of interest for human technology?
•Many spider silks outperform other natural & man-made materials (e.g., steel, Kevlar, elastin, etc.) •Considerable interest in silks as strong, stretchy, light-weight, biodegradable, hypoallergenic biomaterials •Military uses => parachute cords, aircraft materials, bullet-proof vests, etc. -Biomedical uses => artificial ligaments, wound dressings, microsutures, scaffolds for tissue growth, etc.
Describe the research looking at "hookworm soup" and remember this is a nematode
•May alleviate symptoms of autoimmune diseases •Anti-inflammatory protein-2 from worm soup •Maybe parasites aren't always the "enemy"
A phylogeny of Cnidaria helps to explain the distribution of polyp + medusa across the major Cnidarian groups. Explain
•Medusa stage likely evolved to facilitate outcrossing + dispersal in open ocean -Anthozoa (most left)never developed medusa stage •Cubozoa and Scyphozoa (Middle) have reduced polyp •Some Hydrozoa lose polyp
What are the two groups of myriopods and what are a couple differences?
•Millipede • Some of the oldest land animals • Detritivores • Each segment has two pairs of legs • Chemical defenses •Centipede • Carnivores • Each segment has one pair of legs • Claws that paralyze prey ("fangs" with venom)
When we think of animals, we often think of fellow vertebrates but most animals are what?
•Most (34 of 35 groups) comprise INVERTEBRATE ANIMALS!! •A single group (Chordates) includes the Vertebrate Animals
What have made these groups so successful?
•Most insects (and thus most animals) are members of the "Big 4" - partly successful because these taxa use flowers as resources
What are neural crest cells? What are important cell derivatives of neural crest cells? Also use an example from an adult vertebrate
•Neural Crest cells - population of multipotent, migratory developmental cells arising from top margin of neural tube (derived from ectoderm) •Neural Crest cells important in head structures •Also migrate from neural tube along entire body axis => differentiate into important cells/structures along entire body axis •Neural cell derivatives: • Peripheral nervous system • Facial cartilage & bone • Pigment cells
Are horseshoe crabs crustaceans? Why are they of interest in biotechnology?
•No, horseshoe crabs are Chelicerata • Chelicerata also includes: Pycnogonids (sea-spiders) • Arachnids (scorpions, spiders, mites, etc) •They are of interest in biotech because we use them in the medical field for the LAL test (or Limulus amebocyte lysate) • Coagulogen in blood cells • Worth $15,000 per quart • Forms a gel when it encounters endotoxins • Lipoglycans from cell wall of Gram-negative bacteria • Can detect concentrations of one part per trillion
What are key vertebrate features/innovations?
•Notochord ➨ reduced in most Vertebrates (e.g., remnant intervertebral discs in adult humans) •Dorsal hollow nerve cord ➨ Spinal cord plus brain •Pharyngeal slits (and supporting arches) ➨ respiration in aquatic vertebrates (gills) or jaws in jawed vertebrates
What are three main innovations defining Bilateria?
•Organ Systems (primary four - digestive, respiratory, excretory, linked by circulatory) •Bilateral Symmetry and Cephalization (= concentration of feeding organs, sensory and neural structures at the anterior end of body) •Triploblastic => 3 EGCLs
Why is the chitin-based exoskeleton a key to arthropod success?
•Outer waxy layer retains water (*water conservation one of the primary keys to success on land) •Strong, but lightweight material (a supportive skeleton that also allows great mobility) •Varies from very hard to very flexible (flexible joints are KEY to movement)
Contrast and draw the two diploid morphological types found in Cnidaria: polyp versus medusa.
•Polyp - oral side up, typically sessile, benthic habitats • can produce new individuals via asexual budding; in few taxa, polyps are sexual (= producing haploid gametes) • often colonial - many connected individuals produced by asexual budding - e.g. colonial corals •Medusa - oral side down (not always!), free-floating, pelagic habitats (= open ocean) • - sexual (producing haploid gametes) - e.g., most jellyfish
What are the three primary cell types found in sponges, and what are their specific functions?
•Porocytes - cells surrounding pore openings (ostia) •Amoebocytes - food transport thru mesophyll, structural support (e.g., producing spicules) •Choanocytes (collar cells): Engulf bacteria and other food particles by phagocytosis • create water currents and trap microscopic food particles/gametes; also involved in egg & sperm production
Provide details of one example of a conotoxin that has been developed as a drug - e.g., how does the drug work? Why is the drug a nice alternative to morphine?
•Prialt (Primary alternative to morphine) => non-addictive, anti-tolerance treatment for severe chronic pain => selectively blocks voltage-gated calcium channels (which propagate action potentials)
What do genomic analyses reveal about the origin of animals?
•Same •Reveals animals share a single common ancestor •Evidence suggests that animals form a monophyletic-clade: o METAZOA
Talk about the global distribution, prevalence, and impact of Schistosomiasis in humans?
•Schistosoma trematodes are very harmful to humanity => Schistosomiasis (also called Bilharzia) •3 species in the genus Schistosoma: distributed in tropical countries worldwide => so-called "neglected tropical disease" •Causes chronic illness or liver/kidney damage (symptoms in response to egg deposition), ~ 20 million humans severely ill, with over 200 million people infected worldwide (CDC 2015 numbers)
Why are barnacles such odd crustaceans?
•Sessile adults but mobile larvae •Natural adhesive very strong •Shell hardened w/ calcium carbonate
What is significant about proteins found in the choanoflagellate genome?
•Shared parts of genome include proteins for cell signaling and cell adhesion, previously thought to be restricted to animals •Cadherin protein found both in Choanoflagellates and Animals
What is the function of cnidocytes and nematocysts? What is the mechanism of nematocyst discharge in Hydra cnidarians?
•Specialized cells (cnidocytes) fundamental to predatory lifestyle; most cnidocytes house stinging organelles called nematocysts •Nematocysts = organelles, enclosed in cnidocyte cells •Chemical/Mechanical stimulation causes nematocyst to "fire" => threads, coils, toxins subdue prey •How Nematocysts Discharge in Hydra: • Recent research suggests a combination of osmotic pressure (calcium ions moved from nematocyst capsule into cell cytoplasm), plus energy stored in collagen proteins of capsule wall
What are some of the different ways spiders use silk?
•Spider Silks are Produced in Abdominal Silk Glands => produced as liquid proteins •Some spiders have several gland types, each producing silk proteins with different functional properties, used in different ways!! •The Many Functions of Spider Silks: • Egg sacs/Nests • Silken "balloons" to aid in Dispersal • Burrow Protection (e.g., trapdoors) - antifungal properties, concealment, mechanical protection from predators • "Spider webs" - silken constructs used to detect, capture & hold, wrap prey (mostly insects)
Why can't we raise spiders for their silk like we do silkworms?
•Spiders are predators!! •Liquid protein to solid silken fiber transition difficult to replicate
What are some important lineages within Arachnida?
•Spiders, Scorpions, Harvestmen, Solifugae, Schizomids
Schistosoma flukes have three cellular/molecular mechanisms that prevent detection by the host immune system - what are these mechanisms?
•The adult Schistosome tegument => key to success, but also potential Achilles heel •Outer body wall = single syncytium (also called distal cytoplasm, DC) •Evading Detection by Host Immune System: • I) Mask surface with host proteins => "immune masking" • II) Syncytium is NOT a static layer, undergoes frequent transformation • III) Very few parasite proteins expressed exclusively in wall of tegument (=> few targets for host immune response)
Why are tardigrades amazing, and what specific gene did we talk about?
•The most resilient animal known, surviving extreme conditions that would be rapidly fatal to nearly all other known life forms •Withstand EXTREME temperatures •Extreme pressure •Ionizing radiation •Vacuum of space
What are the arachnid ectoparasites that humans deal with?
•Ticks - ectoparasites, vector for Lyme disease (spirochete bacteria) •Mites- generally quite small Diverse, live in all habitats Detritivores, parasites
What does the clade Pancrustacea refer to?
•Traditional "Crustaceans" not monophyletic: includes Hexapoda and hence Insecta also •Remember, much of animal life traces to aquatic environments
Describe and illustrate the complex lifecycle of a Schistosoma fluke. What is the biological significance of larval stages that use intermediate hosts?
•Trematodes (flukes): Vertebrate Animal Endoparasites •Have complex life cycles => use vertebrate animals as primary host (where adults live), but also use one or more intermediate hosts •Intermediate hosts => dispersal agents for reaching new primary hosts - use of IHs requires specialized larval stages •ALL hosts have defense systems (e.g., vertebrate immune system), parasites have evolved mechanisms to overcome defenses, for multiple hosts => parasites highly specialized for a unique lifestyle
What is wing coupling? How does that relate to being an acrobatic flier?
•True Flies (Diptera) with only a single pair of wings => most acrobatic of insect fliers •Other good fliers (e.g., Hymenoptera, bees & wasps) => wings hooked together, function as single unit (Wing Coupling)
What is the defining feature for Eumetazoan animals?
•True tissues => derived from embryonic germ cell layers (EGCLs) •Ex: Cnidaria - jellyfish, corals, relatives
What organisms are echinoderms?
•Unique water vascular system • Tube feet: locomotion & feeding •Important members of marine communities •Impressive regenerative properties •Organisms include: • Asteroidea (Sea stars and sea lilies) - "Radial" symmetry (Re-evolved from bilateral symmetry); Ophiuroids (Brittle Stars); Echinoidea (Sea Urchins); Sand Dollars; and Holothuroidea (Sea Cucumbers)
Most (not all) molluscs share 3 primary features in common. What are these? What are possible functions of these primary features?
•Ventral Muscular Foot (used for locomotion, as holdfast, for feeding) •"Visceral Mass" - houses internal organs (Primary Four organ systems typically present) •Dorsal Mantle - cell layer that secretes shell - protects against predators, prevents mechanical damage, prevents desiccation (*when terrestrial)
What are some primary characters of Chondrichthyes?
•Well developed paired fins and toothed jaw •Counter-current gill respiration (posterior pharyngeal arches retain gas exchange function) •Placoid scales •Mostly cartilaginous endoskeleton •Large,oily liver said in buoyancy(*lack swim bladders)
What other structure are made of chitin cuticle?
•Wings •Cuticular Lenses •Membranes for hearing •Cuticular structures for producing sound
What is the cuticle of arthropods and relatives made of?
•cuticle with structural polysaccharide chitin
Describe and define the function of the lateral line system, and of the Ampullae of Lorenzini.
•for mechanoreception (detecting low frequency vibrations in water) => e.g., water movements caused by struggling fish extremely sensitive hair cells that respond to water displacement LLS also found in ray-finned fishes, lobe-finned fishes, and aquatic amphibians => general system for mechanoreception in aquatic gnathostomes •Sharks & rays detect electrical fields that accompany muscle contractions of prey items!! - Can also use electroreceptors to detect small differences in water temperature => used for navigation (water currents), finding prey that prefer certain water temperatures, etc...
