ZoologyTest3StudyGuide

• Metazoans are the multicellular organisms that form tissues found in the majority of the animal kingdom.
• Metazoa may have evolved from…
• 1. Syncytial ciliated cells: multinucleated cells that had cilia, such as Paramecium.
• 2. Colonial flagellated cells: flagellated cells that functioned as a colony, such as Volvox.
• 3. Monophyletic: belief that multicellular organisms evolved from a single phylum, and not multiple phyla.
• *#2 is most accepted due to Ribosomal RNA sequencing

• Mesazoa: a single phylum which is entirely parasitic of invertebrates (octopuses, squids, etc). Minute, ciliated, wormlike with adults called vermiforms (“wormlike”).
• Parazoa: Developed “parallel” to the metazoans; consists of Porifera (sponges) and Placozoa (glide over their food using digestive enzymes).
• Eumetazoa: “True” metazoans; consists of the rest of the animal kingdom

• Lophotrochozoans, Ecdysozoa, and Deuterostomia.
• Information about Lophotrochozoans…
• Bilateral symmetry
• Triploblastic
• Protostome (“mouth first”)
• Some develop lophophore (ciliated tentacles or crown for feeding)
• Some have trochophore larva
• 18 phyla that include Platyhelminthes (flatworms), Rotifers, Mollusks (squids, clams, snails), Annelids (earthworms, leeches), Acnthocephala (spiny-headed worms), Nemertea.
• Information about Ecdysozoa…
• Animals that shed a tough external coat/cuticle (eg. Arthropods).
• Process is known as molting or ecdysis
• All invertebrates
• 8 phyla that include Nematoda, Arthropoda, and Onychophora
• Information about Deuterostomia…
• Deuterostome (“mouth second”)
• Phyla include Echinoderms (starfish, no vertebrates), Hemichordata (almost vertebrates), and Chordata (vertebrates)

• Sponges
• Filter-feeding through ostia
• Sessile
• Aquatic
• Have many holes on surface (ostia)
• Contain spicules made of Calcium Carbonate, silica, and spongin
• Perform asexual reproduction (budding) and sexual reproduction (sperm and eggs)
• Radial symmetry or no symmetry

• Classified based on types of spicules, shape of sponge, and DNA. NOT BY CANAL TYPES!
• Calcarea: have calcareous spicules (calcium carbonate) which have 3-4 rays. Have tubular or vase shape. Can have asconoid, syconoid, or leuconoid canal system. (Leucosolenia, Scypha)
• Hexactinellida: “glass sponges” have six-rayed siliceous spicules (silicon) (Euplectella aspergillum)
• Demospongiae: “bath sponges” or “horny sponges.” Skeleton of siliceous spicules (silicon), except bath sponges which have spongin (collagen – a protein) instead. Large sponges that have only leuconoid canal system due to size and complexity. Gemmules are released through osculum, and will become a new sponge. (Spongilla, Chalina, Euspongia)

• 1. Water enters through ostia (pores on sides of sponge)
• 2. Microvilli of choanocytes absorb nutrients from water
• 3. Choanocytes transfer nutrients to Amoebocytes
• 4. Amoebocytes phagocytes nutrient, create spicules
• 5. Flagella of choaocytes push water out
• 6. Water exits through osculum (large hole at top of sponge)

• Amoebocyte (Archaeocyte): amoeba-like cells at the base of each choanocyte. Phagocytizes the food transferred from Choanocytes, creates spicules.
• Spicules: embedded into sponge walls to support sponge structure
• Spongocoel: cavity within the sponge
• Porocytes: cells at the tip of ostium that have the ability to close the ostium when the sponge is in danger (eg. Water is poisoned)
• Pinacocyte: cells on outer surface of sponge which help to regulate surface area (look like squamous epithelial cells)
• Choanocytes (collar cells): cells that absorb nutrients from water (via microvilli) and transfer to Amoebocytes. Push water out of the osculum (via flagella)
• Mesoglea (Mesohyl or Mesenchyme): gelatinous area found between pinacocytes and choanocytes

• Asconoids: flagellated spongocoel, simplest canal system (eg. Leucosolenia)
• Ostium -> spongocoel (lined with choanocytes) -> osculum
• Syconoids: flagellated canals, moderate canal system (eg. Scypha, Grantia)
• Ostium -> incurrent canal -> prosopyle -> radial canal (containing choanocytes) -> apopyle -> spongocoel -> osculum
• Leuconoids: flagellated chambers, complex canal system. All freshwater and most marine sponges. (eg. Bath sponge)
• Ostium -> incurrent canal -> flagellated chamber (lined with choanocytes) -> excurrent canal -> osculum

• Also known as Mesohyl or Mesenchyme
• Pinacocytes: Half of cell is in mesoglea
• Choanocytes: bulb portion is in mesoglea
• Amoebocytes: entirely in mesoglea
• Spicules: entirely in mesoglea

• Sclerocytes: secrete spicules
• Spongocytes: secrete spongin
• Collencytes: secrete collagen
• Lophocytes: secrete large amount of collagen

• Asexual: budding and regeneration
• Gemmules are internal buds
• Sexual reproduction: monoecious (hermaphroditic)
• Sperm and oocysts formed from choanocytes
• Some are viviparous
• Some are Oviparous
• NONE are Ovoviviparous

• Viviparous: embryonic development within animal then give birth (mammals)
• Oviparous: lay eggs that require an incubation period (bird)
• Ovoviviparous: lay eggs that hatch immediately, incubation has already taken place inside animal (scorpion, shark)

• Phylum Cnidaria and phylum Ctenophora make up the radiate animals
• Radiate means that they can be cut longitudinally in any direction and both halves are alike (unlike humans with bilateral symmetry)
• Most are sessile
• They make easy meals for other animals (unlike sponges)
• Diploblastic (ectoderm and endoderm), If they have a mesoderm it was derived from ectoderm
• Epidermis formed from ectoderm, gastrodermis formed from endoderm
• Gastrodermis cells are located in gastrovascular cavity
• Simplest animals with nerve cells (unmyelinated)

• Include Hydroids, sea anemones, jellyfish, and horny corals
• Classified into phylum based on presence of cnidocytes
• All aquatic (mostly marine and a few freshwater)
• Two forms of life: polyp (sedentary) and medusa (mobile)
• Majority have mouth, but no anus (waste exits through mouth area – incomplete digestive system)
• Asexual and sexual reproduction
• Epitheliomuscular: epithelial cells are attached to muscle fibers (actin/myosin). DO NOT HAVE MUSCLE CELLS.
• If they have an exoskeleton/endoskeleton it is made of chitin, calcium carbonate, or protein
• Have gastrovascular cavity
• Ciliated, mobile, larva called planula
• Have a nerve net (unmyelinated nerve cells, neurotransmitters, and neuromuscular system. No brain.)

• Hydrozoa: Obelia, Hydra, Gonionemus, Physalia, Polyorchis
• Scyphozoa: Aurelia
• Cubozoa: Carybdea marsupialis
• Anthozoa: Metridium, coral

• Polyp: sedentary, tubular, has aboral end (point of attachment) and oral end (mouth), some form colonies – gonozoite (reproduction), dactylozoite (defense), and gastrozoite (feeding), large gastrovascular cavity
• Medusa: mobile, bell shape/umbrella shape, mouth is in center of animal, mesoglea is thicker than polyp stage, aboral end (top of umbrella), oral end (mouth), small gastrovascular cavity

• Cnidocyte houses the nematocyst (weapon) internally, like an organelle
• Cnidocil: small nub at tip of cnidocyte, causes operculum to open when stimulated by nerve.
• Operculum: flap/lid of nematocyst capsule, when operculum opens the filament is released
• Filament: can have various functions, based on the type of nematocyst…
• Pentrants: penetrate and inject poison
• Volvents: entangle prey, and bring prey to mouth for digestion
• Glutinants: release adhesive substance used for locomotion and attachment

Interstitial cells are found in Cnidarians, are pluripotent, and give the Cnidarians regenerative abilities. Interstitial cells can differentiate into spermatozoa, cnidocytes, or nerve cells, but CANNOT differentiate into epithelial cells or nutritive muscle cells.

• Genera include Obelia, Hydra, Gonionemus, and Physalia
• Some have medusa, polyp, or both
• Mostly marine, but freshwater Hydra
• Colonial (Obelia, Physalia)
• Have velum (a membrane on the subumbrella surface of medusa) which allows swimming, only found in Hydrozoans

• Only polyp stage
• freshwater (not marine)
• solitary (not colonial)
• multiply sexual AND asexually
• small size
• sedentary (not mobile)

• Freshwater
• Asexual reproduction by budding
• Testis and ovaries for sexual reproduction (monecious)
• Epidermis, Gastrodermis, and mesoglea (3 layers)
• Mouth opens to gastrovascular cavity
• Interstitial cells (regenerative abilities)
• Polyp only

• Marine
• Medusa is mature (reproduces in this stage)
• Gonads attach to radial canal
• External fertilization (in environment)
• Polyp stage may undergo asexual reproduction (budding) or may form medusa.

• Marine
• Sexual stage is free-swimming medusa
• Medusa similar to Gonionemus, but smaller
• Colonial (gastrozoite, gonozoite, and dachtylozoite)
• Hydrocaulus: main stalk/trunk of polyp stage
• Perisarc: dead material, found on periphery of hydrocaulus. Made of chitin (glucose molecule w/ N attached)
• Coenosarc: living material, found in center of hydrocaulus
• Lifecycle…
• Medusa buds are released from gonozoite, and become mature medusa. Medusa sexually reproduce through external fertilization, which results in ciliated, free-swimming, planula (larval stage). Planula attaches to sea floor and becomes immature polyp. Polyp becomes mature polyp with colonies.

• Common name – Portuguese Man-of-War
• Polymorphism: has many shapes (essentially colonial)
• Looks like a single animal, but is made up of gastrozoite, gonozoite, and dachtylozoite
• A single colony has both polyp and medusa

• Genera include Aurelia
• Commonly called “true jellyfish”
• All marine
• Most large jellyfish belong to this class (polyp is absent or reduced)
• Sexes are separate, gametes released to gastrovascular cavity
• Internal fertilization
• Zygote on oral arms of medusa OR in sea water
• Ciliated planula (larva) -> scyphistoma (polyp-like stage) -> strobila (stack of 11-12 ephyra) -> ephyra (immature medusa) -> medusa
• No velum in medusa, but still able to move
• One order is sessile

• Species include Carybdea marsupialis
• Commonly called “sea wasps”
• Umbrella looks like a cube
• Have velarium (similar function to velum of Hydrozoa)
• Polyp is small
• No ephyra, there is a metamorphosis directly to medusa stage
• Stinging is dangerous to human, can kill (textbook says most venomous animal on planet)

• Metridium, thorny corals
• Commonly called “flower animals” due to vibrant colors in tentacles
• All marine
• Polyps only, medusa absent
• Pharynx or gullet present (mouth)
• Gastrovascular cavity has 6 complete septa, several incomplete septa
• Mesoglea has amoeboid cells
• Use nematocysts for defense/hunting
• Asexually reproduce by pedal laceration and lateral fission
• Coral reefs created when corals absorb/deposit calcium carbonate from ocean around themselves. When the animal dies, coral reef remains.

• Commonly called “comb jellyfish”
• Genera include Pleurobrachia
• Resemble Cnidarians: radial symmetry, aboral-oral axis, well developed mesoglea, no coelomic cavity, nerve plexus, lack of organ system, no respiratory system
• Differences: No nematocysts, have distinct muscle cells, have comb plates (can generate electricity, generate light), no polymorphism (only one stage), never colonial, have anal pore (on aboral end), smaller amount of species

• Coelum: space between gut and epidermis completely surrounded by mesoderm
• Acoelomate: “without coelum” – space between gut and epidermis is FILLED with mesoderm
• Pseudocoelomate: “false coelum” – space between gut and epidermis has mesoderm only on outside (other side is endoderm).
• Eucoelomate: “true coelum” – space between gut and epidermis is completely surrounded by mesoderm.

• Some cephalization (have head)
• Bilateral symmetry
• Have true organs
• Protostome (“mouth first”)
• Spiral cleavage
• Simplest excretory and circulatory system
• Triploblastic – Mesoderm in the form of parenchyma (muscle fiber and mesenchyme)
• Three phyla – Platyhelminthes, Nemertea, Gnathostomulida

• Triploblastic (Mesoderm in form of parenchyma layer)
• Bilateral symmetry (Flat dorsoventrally)
• Incomplete digestive system in some (mouth, no anus) – waste can exit through mouth OR diffuse through body walls OR flame cells -> excretory canal -> excretory duct
• Free-living and parasitic
• Most monogenea are ectoparasitic of fish (cause infestation)
• All digenea and cestoda are endoparastic (cause infection)
• Most are monecious (hermaphroditic) – not Schistosoma
• Indirect (needs vector) and direct lifecycles
• Definitive host is vertebrates in most cases (sexual reproduction occurs)
• Some have eyespots (light intensity, not image-forming)
• True muscles
• Body fluid moves by muscular contraction (similar to skeletal-muscle pump for veins)

• Turbellaria: Dugesia
• Trematoda:
• Subclass Digenea: Fasciola hepatica, Fasciolopsis buski, Clonorchis sinensis, Schistosoma mansoni, Shistosoma japanicum, Shistosoma haematobium, Paragonimus westermani
• Subclass Monogenea: Gyrodactylus cylindriformis
• Cestoda: Taenia saginata, Taenia solium, Diphyllobothrium latum, Echinococcus granulosus, Dipylidium caninum

• Planarians (eg. Dugesia)
• Free-living
• Mostly marine
• Epidermis is ciliated on ventral side
• Mouth on ventral side, no anus (incomplete digestive system)
• Metabloic waste by diffusion through the body wall OR flame cells OR mouth
• Simple life cycle
• Osmoregulation required for Planaria because water is constantly entering (like Paramecium)
• Flame cells (part of excretory system) remove water and waste (ammonia) for osmoregulation
• Three types of neurons: sensory, motor, and association
• Have neural ganglia, NOT brain
• Asexual regeneration (cut in half = 2 organisms)
• Monoecious, but practice cross fertilization to increase genetic variability
• Fertilization is internal, and occurs in female oviduct
• Carnivorous heterotrophs
• Ocellia (light-sensitive eyespot)
• Rhabdites cells (release mucus to ease locomotion)
• Three types of muscle: longitudinal, circular, and radial
• Gastrodermis has phagocytes to engulf food
• Protonephredia = flame bulbs
• Pharynx (in middle of animal) can extend and act as a vacuum for food.

• Common name “flukes”
• All parasitic
• Tegument (“skin”) has no cilia and is syncytial (mutli-nucleated)
• Have two suckers (oral and ventral)
• Poorly developed sense organs
• Subclasses Digenea and monogenea

• Require two hosts (intermediate host and definitive host)
• Species include Fasciola hepatica, Fasciolopsis buski, Clonorchis sinensis, Schistosoma sp., Paragonimus westermani
• General lifecycle: egg (contains miracidium) -> miracidium (ciliated larval stage that escapes egg, gets into water, and finds/penetrates snail) -> sporocyst (in snail, contains many rediae) -> rediae (in snail, contains many cercariae) -> cercariae (ciliated larva that gets out of snail) -> metacercaria encyst on vegetation or meat of fish -> adult in human
• This type of lifecycle allows a single egg to rise to MANY progeny. Since odds of infection are not high, this increases odds of survival. Flukes are only animal where single egg can become multiple organisms.
• Stopping the spread of flukes requires removing one of their intermediate hosts from the environment.

• Disease common name is “liver rot”
• Phlylum Platyhelminthes, class Trematoda, subclass Digenea
• Animals (sheep, cow, etc) Not typically found in human
• Causes large white spots on liver of animal. Animal probably got infected by eating grass that had metacercaria.
• Lifecycle: Cow poops egg -> egg in water -> miracidium escapes egg, find snail (Lymnea) -> penetrates snail -> becomes sporocyst within snail -> many rediae develop from single sporocyst -> inside rediae are many cercariae -> cercariae exits, finds vegation -> becomes metacercaria -> eaten by cow -> matures to adulthood in liver of cow -> cow poops egg…

• Phlylum Platyhelminthes, class Trematoda, subclass Digenea
• Found in human small intestine
• Lifecycle same as Fasciola hepatica
• Larger than Fasciola hepatica

• Common name “Human liver fluke”
• Phlylum Platyhelminthes, class Trematoda, subclass Digenea
• Lifecycle: human poops egg -> egg in water -> miracidium escapes egg, find snail -> penetrates snail -> becomes sporocyst within snail -> many rediae develop from single sporocyst -> inside rediae are many cercariae -> cercariae exits, finds fish -> penetrates fish, becomes metacercaria -> eaten by human -> matures to adulthood in bile duct of human -> human poops egg…
• Note – Metacercaria found in meat of fish, not vegetation
• Human can only become infected through ingestion of infected fish (Cooking will kill – pickling will not)
• Doesn’t harm fish
• Adult in bile duct, doesn’t cause an issue if only a few, but many will block the bile duct
• Issue in rural areas of far eastern countries

• Constantly change surface protein molecules, making host antibodies useless
• Can absorb food THROUGH tegument

• Phlylum Platyhelminthes, class Trematoda, subclass Digenea (Old name Bilharzia)
• Common name “blood flukes”
• Dioecious w/ male bigger (wider) than female
• Male has gynecophoric canal – females enter and reside during reproduction
• S. mansoni: found in blood vessels of large intestine. Can kill humans. [far eastern countries]
• S. japanicum: in blood vessels of small intestine. Can kill humans. [far eastern countries]
• S. haematobium: in blood vessels of urinary bladder. Causes bloody urine (maturity in old Egypt). [Middle east/North African countries]
• Cause ulceration in intestine, bladder
• Can cause dwarfing
• Schistosoma Dermatitis: (disease, not species) Schistosoma of a bird exits in feces, gets into water, cercaria enter human causing an itch, but die within 24 hours. [North America]
• Do not have metacercaria and rediae stages
• Lifecycle: human poops egg -> egg in water -> miracidium escapes egg, find snail -> penetrates snail -> becomes sporocyst within snail -> inside sporocyst are many cercariae -> cercariae exits, finds human -> matures to adulthood in human -> Schistosoma sexually reproduce -> human poops egg…
• Cercaria have branched tails
• Method of biological control would be crayfish, to remove the snails (intermediate hosts)

• Schistosomiasis, malaria, filariasis, trypanosomiasis, leishmaniasis, and leprosy
• 5 are parasites, only 1 (leprosy) is bacteria

• Phlylum Platyhelminthes, class Trematoda, subclass Digenea
• Common name “lung flukes”
• Adult fluke resides in lungs (human)
• Crab/crayfish is intermediate host – metacercaria reside in meat. Human is definitive host (infection from eating crab or crayfish without cooking)
• Metacercaria stage goes to human lung and matures into adults
• Two methods of egg release…
• 1. Escape through sputum (cough up/sneeze)
• 2. Sputum is swallowed, egg goes to digestive system, excreted in feces.
• Either way, egg gets into water and lifecycle is continued

• Species include Gyrodactylus cylindriformis
• All parasitic on gills or external surface of fish, suck blood of fish
• Ectoparasitism and infestation (outside) NOT infection (inside)
• Direct life cycle, single host (just fish)
• Egg -> single larva (oncomiracidium) -> matures on gills of fish -> adult -> detaches and makes eggs
• Opisthaptor: structure that attaches to fish gills and sucks blood

• Species include Taenia saginatus, Taenia solium, Diphyllobothrium latum, Echinoccous granulosus, Dipylidium caninum
• Commonly named “tapeworms”
• Three major parts: scolex (“head area” that has can have suckers and/or hooks for attachment), germinative zone (“neck area” where asexual reproduction occurs, lengthening tapeworm), strobila (“tail area” consisting of chains of proglottids)
• Scolex may contain rostellum (elevation of scolex)
• Immature proglottids -> mature proglottids (have testes, ovary, yolk gland, etc) -> gravid/ripe proglottids (uterus filled with eggs fills proglottid and all other structures disintegrate)
• Gravid proglottids are ‘released’ by the cestode and exit in the feces, releasing eggs.
• Nearly all are monoecious (hermaphroditic)
• Cross fertilization is possible
• Adults are found in vertebrates, intermediate hosts are invertebrates
• Nearly all organisms can have a tapeworm (different species)
• No digestive system, food absorbed through tegument
• In general, do not harm host simply compete for food.

• Phylum Platyhelminthes, class Cestoda
• Common name “beef tapeworm”
• Intermediate host – cattle, definitive host – human
• Does not harm human
• Scolex has 4 suckers, no hooks
• Cysticercus (larval stage, infective for human) in beef
• Excretory ducts have flame cells
• Life cycle: egg -> oncospheres -> bladder worm or cysticercus (in cattle) -> cysticerci becomes adult and sheds gravid proglottids (in human)
• Human ingest cysticerci from uncooked infected beef, cattle ingest egg from human feces

• Phylum Platyhelminthes, class Cestoda
• Common name “pork tape worm”
• Intermediate host – pig OR human, definitive host – human
• Cerebral cysticercosis: cysticercus in human can go to brain rather than other parts of the body causing devastating effects. Cannot be removed by surgery.
• Scolex has rostellum, suckers, and hooks
• Life cycle: egg -> oncospheres -> bladder worm or cysticercus (in pig) -> cysticerci becomes adult and sheds gravid proglottids (in human)
• Note – cysticercus is also possible in human IF human ingests egg. (egg -> cysticercus)

• Phylum Platyhelminthes, class Cestoda
• Intermediate host – fish, definitive host – human
• Competes with vitamin B12, which is needed for proper RBC production.
• Causes megaloblastic/pernicious anemia (RBCs become huge, unable to fit into capillaries)
• Lack of gas exchange results in lethargy, tiredness, etc but not death.
• Scolex has longitudinal grooves (no suckers/hooks)
• Cysticercus in fish
• Infection by eating infected raw fish (especially in the Great Lakes area)

• Phylum Platyhelminthes, class Cestoda
• Definitive host – dogs and other canine, intermediate host – human
• Hydatid cyst: cysticercus in human becomes HUGE. Can only be removed by surgery (no medication). If hydatid cyst ruptures during surgery, patient will die instantly from anaphylactic shock.
• Smallest tapeworm in class, only 3 segments. Entire animal less than 1 cm.
• Possible infection by petting dog who has rolled in its infected feces -> eggs on hand -> hand in mouth
• Hydatid cyst can be formed in stomach, brain, arms, etc. Doesn’t HAVE to be one area.

• Phylum Platyhelminthes, class Cestoda
• Common name “dog tapeworm”
• Children can contract, but adult immune system will easily destroy. Would contract by eating infective flea.
• Intermediate host – flea, definitive host – dogs (mostly), some cats
• Gravid proglottids look like rice granules
• Good method of prevention is to place mothballs into a vacuum bag when vacuuming. This will kill the fleas, and end the cycle.

• Do not harm hosts (in general)
• No GI tract, absorb nutrients through tegument
• Have cuticle to prevent digestion
• Have hooks/suckers for attachment to host
• Asexual reproduction results in thousands of eggs released in an “assembly line” type fashion via proglottids

• T. solium: Intermediate host pig/human, definitive host human, cerebral cysticercosis, uterus branches less than seven times, scolex has 4 suckers/hooks/rostellum
• T. saginata: Intermediate host cow, definitive host human, does not harm human, uterus branches more than seven times, scolex has 4 suckers/no hooks

-Flame cells (gather waste from acoelomate area) -> excretory duct -> excretory pore)