Zoology Exam III
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What are theories that metazoans came from?
- Metazoa are multicellular organisms and came from unicellular organisms
- - 3 theories that metazoa originated from
- 1. Syncytial (multi-nucleated) ciliated cells
- 2. Colonial flagellated cells e.g. Volvox
- 3. Monophyletic
What is the most reliable technique that proves the above theory?
- Ribosomal RNA sequencing supports theory #2 and is most accepted amongst scientists
What are the three grades of metazoa?
- - There are three grades of metazoa:
- 1. Mesazoa: one phylum, all parasitic
- 2. Parazoa: Porifera & Placozoa
- 3. Eumetazoa: the rest of animal kingdom
What are characteristics of phylum Mesazoa?
- - Minute, ciliated, wormlike
- - All parasitic of invertebrates e.g. octopuses, squids, etc.
- - Adults are called vermiforms (worm-like)
What are characteristics of phylum Parazoa?
- Glide over their food using digestive enzymes
What are the charactersitics of clade lophotrochozoans?
- Major clades: Lophotrochozoans, Ecdysozoa, & Deuterostomia
- - Bilateral symmetry, triploblastic and protostome
- - Some develop lophophore: ciliated tenticles or crown for feeding
- - Some trochophore larva
- - 18 phyla in this clade: Platyhelminthes (flatworms), rotifers, molluscs & annelids, acanthocephala, nemertea
What are the charactersitics of clade ecdysozoa?
- - Animals that shed a tough external coat, cuticle
- - Molting or ecdysis (invertebrates)
- - Eight phyla, Nematoda, arthropoda, onychophora
What are the charactersitics of clade deuterostomia?
- - Echinoderms
- - Hemichordata
- - Chordata
What are the characteristics of sponges?
- - Filter-feeding system by ostia
- - Sessile and all aquatic
- - Spicules made up of calcium carbonates,
- silica and spongin
- -Asexual and sexual reproduction
Why are the sponges called porifera?
- Many holes under the surface of the body
Why are sponges not good meals for other fishes?
- - Have spicules and spicules are like bones in the human body, provide structure and is hard and spiny
- - Skeletal system too prickly and also obnoxious odor
What are the four classes of sponges?
- Calcarea: with calcareous (calcium carbonate) spicules
- Hexactinellida: six-rayed siliceous (silicon) spicules
- Demospongiae: skeleton of siliceous spicules
- - Sclerospongiea: calcareous skeleton and
- siliceous spicule
What are characteristics of Calcarea?
- - Spicules are calcium carbonate, have 3 to 4 rays
- - Tubular or vase shape
- - Spicules form a fringe around the osculum
- - All 3 types of canal systems, all marine
- - E.g. Sycon, Leucosolenia, Clathrina
What are characteristics of Hexactinellida?
- - Skeleton of six-rayed siliceous spicules
- - Body often cylindrical or funnel-shaped
- - Glass sponges
- - Habit mostly deep water, all marine
- - E.g. Venus' flower basket (Euplectella), Hyalonema
What are characteristics of Demospongiae?
- - Large sponges: bath/horny sponges
- - Siliceous and all leuconcoid
- - Leave gemmules behind
- - Bath sponges lack siliceous spicules, they have spongin instead
- - One family found in freshwater, all others are marine
- - E.g. Amphimedon, Cliona, Spongilla, Myenia, Poterion and other bath sponges
What are characteristics of Sclerospongiea?
- - Spicules may be absent
- - Small group
- - Calcareous skeleton: coralline sponges
- - E.g. Oscarella, Corticium
What are the three types of canals in porifera?
- Asconoids: flagellated sponges, simplest
- Synconoids: flagellated canal, larger edition of asconoids
- - Leuconoids: flagellated chambers water
- current is through
- - All freshwater & most marine sponges
What are the different types of cells in porifera?
- Pinacocytes: helps to regulate surface area of sponge, epithelial cell-like on surface
- Choanocytes: straining food particles
-Archaeocytes: phagocytize the food
- Types of archaeocytes:
- - Sclerocytes: secrets spicules
- - Spongocytes: spongin
- - Collencytes: collagen
- - Lophocytes: large collagen
What are different types of cells in mesoglea layer?
- Pinacocytes, choanocytes and archaeocytes
Explain filter feeding of porifera and passage of water in sponges?
- - Water enters the ostium
- - Incurrent canal
- - Porocytes
- - Radial canal
- - Apopyle
- - Spongocoel
- - Osculum
How do sponges multiply?
- Asexual and sexual reproduction
- Asexual by budding and regeneration
- Gemmules: internal bud
- Sexual reproduction: monoecious (hermaphroditic)
-Sperm and oocysts are formed from choanocytes
- Zygote in parents called viviparous (give birth)
- Oviparous (lay eggs)
- Ovoviparous (egg immediately hatches after laying) e.g. shark and scorpion
What are the skeletons of sponges made up of?
- Sporigin (collagen), calcium carbonate and silica
Sponges are classified based on what?
- RNA, shape and spicules
- Not canal type
What are main characteristics of radiate animals?
- - All aquatic
- - Two forms of life: polyps and medusae
- - Exoskeleton or endoskeleton of chitinous, calcareous or protein
- - Gastrovascular cavity
- - Mouth, anus and tentacles
- - Cnidocytes contain the nematocytes (their weapons)
- - Epitheliomuscular
- - Asexual and sexual
- - Planula larva
- - No respiratory or coelomic cavity
- - Most are sessile
- - Easy meals for other animals
- - Can injure human, cause death
- - Ectoderm and endoderm
- - Simplest animal with nerve cells
What are different types of colony in radiate animals?
- Gastrozooids: feeding colony
- Dactylozooids: defense colony
- Gonozooids: male and female, reproductive colony
What are the characteristics of phylum cnidarians?
- - Mostly marine and a few freshwater
- - Radial/biradial symmetry
- - Polyps and medusa
- Nerve net: neurotransmitter, no myelin, neuromuscular system
- E.g. Hydroids, sea anemones, jellyfishes and horny corals
What are the classes of cnidarians?
- 1. Hydrozoa
- 2. Scyphozoa
- 3. Cubozoa
- 4. Anthozoa
What are the differences between medusa stage and polyp stage?
- A. Polyp or hydroids are sedentary
- - Aboral & oral end, attach to ocean floor
- - Tubular
- - Some form colonies
- B. Medusa
- - Bell shape or umbrella, motile
- - Mouth in the center
- - Mesoglea is thicker
What are the characteristics of the cnidocytes?
- Cindoctyes contain: nematocytes, operculum and are born in invaginations in ectodermal cells
- Nematocyst injects toxin for prey capture and defense
- Nematocysts = tiny capsules made of stuff like chitin, end of capsule covered by operculum (little lid)
- - 3 types of nematocytes
- 1. Penetrants: penetrate & inject poison
- 2. Volvents: entangle prey
- 3. Glutinants: adhesive substance for locomotion & attachment
What are the characteristics of class hydrozoa?
- E.g. Obelia, Hydra, Gonionemus, Physalia
- Some have medusa, polyp or both stages
- Colonial; mostly marine but there are freshwater Hydra
- Velum: a membrane on the subumbrella surface of jellyfish of class hydrozoa
What are the 5 differences between Hydra and the rest of the Hydrozoa?
- - Live in freshwater
- - Regenerative
- - Do not age/die of old age
- - Mouth opens to gastrovascular cavity
- - Have testes and ovaries
- - Budding
- - Interstitial cells
What are the characteristics of Gonionemus?
- Marine hydromedusa or hydrozoan jellyfish
- Medusa is mature
- Gonads attach to radial canal
- External fertilization
- Polyp stage might undergo asexual reproduction by budding or may form medusa
What are the characteristics of Obelia?
- Colonial marine hydrozoan
- Sexual stage is free-swimming medusa
- Medusa similar to Gonionemus but smaller
What are the characteristics of Physalia?
- Portuguese man-of-war
- - Look like a single animal, but made up of:
- •Feeding colony
- •Reproductive colony
- •Defensive colony
- Find float and crest
- A single colony has both polyp and medusa
What are characteristics of class scyphozoa?
- All marine, e.g. Aurelia
- Most of large jellyfish, polyp stage absent or reduced
- One order is sessile
- No velum in medusa
-Sexes are separate, gametes released to gastrovascular cavity
- Fertilization is internal
- Ciliated planula --> scyphistoma --> strobila --> ephyra --> medusa
- - Zygote on oral arms of medusa or
- in sea water
What are characteristics of Aurelia?
- - All marine
- - Most are large jellyfish
- - Have polyp and medusa stage
- - Short tentacles
- - Food caught by mucus
- - No velum on medusa
- - 4 oral arms & oral tentacles
- - Square mouth
- - 4 gonads
- - Radial canals
- - Marginal tentacles
What are characteristics of cubozoa?
- - Commonly called sea wasp
- - Stinging dangerous to human
- - Polyp is small and no ephyra, metamorphosis directly to medusa
- - E.g. Carybdea marsupialis
What are characteristics of Anthozoa?
- - Flower animals
- - All marine
- - Pharynx or gullet present
- - Polyps only, medusa absent
- - Tube anemones and thorny corals
- - Gastrovascular cavity has septa
- - Mesoglea has ameboid cells
What are the similarities between Ctenophora and Cnidarians?
- - Radial symmetry
- - Aboral and oral grooves
- - Well-developed mesoglea
- - No coelomic cavity
- - Nerve plexus
- - No organ system
How are Ctenophora different from Cnidarians?
- - No nematocytes
- - Distinct muscle cells
- - Comb plates
- - No polymorphism or dimorphism
- - Never colonial
- - Anal pore
What are characteristics of acoelomates?
- - Coelom: fluid-filled space between gut and epidermis, surrounded by mesoderm
- - Coelom filled with mesoderm
- - Some cephalization
- - Bilateral symmetry
- - Platyhelminth or flat worms
- - True organs
- - Protostome & spiral cleavage
- - Simplest excretory & circulatory system
- - Mesoderm in form of muscle fiber & mesenchyme (parenchyma)
What are characteristics of pseudocolomates?
- One part of coelom surrounded with endoderm and the other part by mesoderm
What are characteristics of eucoelomates?
- Fluid-filled space between gut and epidermis
What are characteristics of Platyhelminthes?
- - Tripoblastic
- - Bilateral symmetry
- - Flat dorsoventrally
- - True muscles
- - Incomplete digestive system in some
- - Some have eye spots
- - Most monoecious
- - Parenchyma cells
- - Most monogenea are ectoparasitic
- - All trematodes & cestoda are endoparasitic
- - Indirect and direct life cycle
- - Final host is vertebrates in most cases
- - Tripoblastic, Cnidarians were not
- - Body fluid moves by muscular contraction
What are characteristics of class turbellaria?
- - Free-living, mostly marines
- - Planarians
- - Epidermis ciliated on ventral side
- - Mouth on ventral side, no anus
- - Simple life cycle
- - Gastrodermis has phagocytes
- - Planaria excrete water out, cause no anus
- - Rid of waste though mouth, excretory pores & tegument
- - Flame cells for osmoregulation
- - Three types of neurons: sensory, motor & association
- - Ocellia or light-sensitive eye spot
- - Asexual regeneration
- - Turbellarians are monoecious but practice
- cross fertilization
- - Fertilization in female oviduct
- - Carnivorous
- - Metabolic waste by diffusion through the body wall
- - Rhabdites cells
- - Three types of muscle: longitudinal, circular & radial
- - Parenchyma cells
- - Protonephredia = flame bulbs
What are characteristics of class trematoda?
- - All parasitic flukes
- - Tegument
- – Has no cilia
- – Syncytial
- - Two suckers
Give 2 reason why tegument is beneficial to platyhelminthes?
- - Surface of organism changes constantly to avoid being killed by auto-immune systems of host
- - Absorbs food/nutrients
- - Increases surface area
Why life cycle of the platyhelminthes is in such a way?
Egg --> miracidium (get into snail) --> sporocytst (in snail) --> rediae (in snail) --> cercariae ciliated larva --> metacercaria encyst on vegetation or meat --> adult
- Single egg can rise to many progeny
Name all the diseases associated with platyhelminthes?
- - Fasciola hepatica - found in US, sheep liver fluke
- - Fasciolopsis buski - found in US, intestinal fluke (human)
- Clonorchis sinensis
- not found in US, human liver fluke
- - Schistosoma mansioni - found in Africa, South/Central American, blood flukes (bloody urine), cause dwarfism
- - Schistosoma japanicum - found in East Asia
- - Schistosoma haematobium - found in Africa
- - Schistosoma dermitis - found in US, bird's dropping have eggs and fall in water, go into skin but just causes rash, can be easily cured
- Paragonimus westermani
- found in US, lung fluke
Do class mongenea cause any problems to humans? If not, explain.
- - Not harmful to humans
- - All parasitic on gills or external surface of fish
- - Ectoparasitic
- - Direct life cycle
- - Egg --> larva --> omcomiracidium --> adult
- - Gyrodactylus cylindriformis
What are the most devastating cestods? Explain.
List 4 or more adaptive techniques that cestods developed to be successful?
- - Proglottid: middle section w/ both male/female reproductive systems
- - Scolex: helps it to hook on and stay in host
- - Tegument: increase surface area, food and nutrients are absorb through this
- - The way the animal is set up from head to toe and in middle is where asexual reproduction takes place (cloning) occurs in scolex, adds segments
- - Cannot mature in host if there is already an adult of that same species
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