Zoology Exam III

- 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

- Ribosomal RNA sequencing supports theory #2 and is most accepted amongst scientists

• - There are three grades of metazoa:
• 1. Mesazoa: one phylum, all parasitic
• 2. Parazoa: Porifera & Placozoa
• 3. Eumetazoa: the rest of animal kingdom

• - Minute, ciliated, wormlike
• - All parasitic of invertebrates e.g. octopuses, squids, etc.
• - Adults are called vermiforms (worm-like)

- Glide over their food using digestive enzymes

- 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

• - Animals that shed a tough external coat, cuticle
• - Molting or ecdysis (invertebrates)
• - Eight phyla, Nematoda, arthropoda, onychophora

• - Echinoderms
• - Hemichordata
• - Chordata

• - Filter-feeding system by ostia
• - Sessile and all aquatic
• - Spicules made up of calcium carbonates,
• silica and spongin
• -Asexual and sexual reproduction

- Many holes under the surface of the body

• - 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

- Calcarea: with calcareous (calcium carbonate) spicules

- Hexactinellida: six-rayed siliceous (silicon) spicules

- Demospongiae: skeleton of siliceous spicules

• - Sclerospongiea: calcareous skeleton and
• siliceous spicule

• - 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

• - 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

• - 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

• - Spicules may be absent
• - Small group
• - Calcareous skeleton: coralline sponges
• - E.g. Oscarella, Corticium

- Asconoids: flagellated sponges, simplest

- Synconoids: flagellated canal, larger edition of asconoids

• - Leuconoids: flagellated chambers water
• current is through
• - All freshwater & most marine sponges

- 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

- Pinacocytes, choanocytes and archaeocytes

• - Water enters the ostium
• - Incurrent canal
• - Porocytes
• - Radial canal
• - Apopyle
• - Spongocoel
• - Osculum

- 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

- Sporigin (collagen), calcium carbonate and silica

- RNA, shape and spicules

- Not canal type

• - 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

- Gastrozooids: feeding colony

- Dactylozooids: defense colony

- Gonozooids: male and female, reproductive colony

• - 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

• 1. Hydrozoa
• 2. Scyphozoa
• 3. Cubozoa
• 4. Anthozoa

• 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

- 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

- 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

• - Live in freshwater
• - Regenerative
• - Do not age/die of old age
• - Mouth opens to gastrovascular cavity
• - Have testes and ovaries
• - Budding
• - Interstitial cells

- 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

- Colonial marine hydrozoan

- Sexual stage is free-swimming medusa

- Medusa similar to Gonionemus but smaller

- Portuguese man-of-war

- Polymorphism

• - 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

- 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

• - 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

• - Commonly called sea wasp
• - Stinging dangerous to human
• - Polyp is small and no ephyra, metamorphosis directly to medusa
• - E.g. Carybdea marsupialis

• - 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

• - Radial symmetry
• - Aboral and oral grooves
• - Well-developed mesoglea
• - No coelomic cavity
• - Nerve plexus
• - No organ system

• - No nematocytes
• - Distinct muscle cells
• - Comb plates
• - No polymorphism or dimorphism
• - Never colonial
• - Anal pore

• - 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)

- One part of coelom surrounded with endoderm and the other part by mesoderm

- Fluid-filled space between gut and epidermis

• - 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

• - 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

• - All parasitic flukes
• - Tegument
• – Has no cilia
• – Syncytial
• - Two suckers

• - Surface of organism changes constantly to avoid being killed by auto-immune systems of host
• - Absorbs food/nutrients
• - Increases surface area

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

• - 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

• - Not harmful to humans
• - All parasitic on gills or external surface of fish
• - Ectoparasitic
• - Direct life cycle
• - Egg --> larva --> omcomiracidium --> adult
• - Gyrodactylus cylindriformis

- Tapeworms

• - 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