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34 Cards in this Set
- Front
- Back
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bilateral symmetry
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symmetry achieved only on one plane
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Baüplane
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(Ger., "body plan") blueprint for the way the body of an organism is laid out. An organism's symmetry, its # of body segments & # of limbs are all aspects of its body plan
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cephalization
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the development of a "head" where most organs that sense the environment and also feeding organs are located
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Directions associated with bilateral animals
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Anterior - toward the head
Posterior - toward the tail/anus Dorsal - towards the top half Ventral - toward the bottom half |
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Triploblastic
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having 3 layers of cells, the endoderm (innermost), the ectoderm (outermost), and the mesoderm, where most organs are
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coelom
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a body cavity, usually a major, central one
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acoelomates
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do not have a coelom, or body cavity
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Lophotrochozoa
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triploblastic, bilaterally symmetric animals which either lack a cuticle or don’t shed their cuticle
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Ecdysozoa
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triploblastic, bilaterally symmetric animals which have a cuticle and periodically shed it
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Deuterostomia
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animals with a unique developmental pathway differing from all other groups
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Key characteristics of Phylum Platyhelminthes
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- triploblastic, with a parenchyma
- acoelomate - most unsegmented - have organs but incomplete digestive tract (single opening) - true nervous system w anterior ganglia and longitudinal nerves - Protonephridia for excretion, osmoregulation - Reproductive organs (most are monoecious) |
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parenchyma
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spongy mass of mesoderm cells in Phylum Platyhelminthes
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Protonephridia
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tubules involved in osmoregulation. at their ends are FLAME CELLS, which are ciliated and create negative pressure to bring water into the tubules
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Classes of Phylum Platyhelminthes
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1 Class Turbellaria - flatworms
2 Class Monogenea - monogenetic flukes 3 Class Trematoda - common fluke 4 Class Cestoidea - tapeworms |
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Class Turbellara Characteristics
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- free living bottom dwellers
- have ciliated epidermis - move w cilia & muscle undulations (muscles more important) - most are carnivores - digestion partly internal, partly external - Take in food via the pharynx on the ventral side, which can be extended (everted) or contracted in some species - Gut may be branched, unbranched, or absent |
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Osmoregulation
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ability to regulate/control water balance and ion levels
-marine species are near osmotic equilibrium/isotonic or isosmotic) with environment - freshwater Turbellaria are hyperosmotic/hypertonic to the environment |
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Osmosis
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movement of water molecules from an area with greater concentration (hyperosmotic) of water to a lower concrentration area (hyposmotic) to attempt to achieve equilibrium (called isosmosis). Via diffusion, usually through a membrane or similar surface.
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Osmoregulation in Turbellaria
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- specialized organs - protonepharia, flame cells
- at end of protonepharia tubules, these cells' cilia create negative pressure, drawing water in. |
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Nervous system of Class Turbellaria
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-nerve nets (like cnidarians) to nervous systems with nerve cords with lateral branches
-Nervous tissue concentrated anteriorly in pair of cerebral ganglia (primitive brain) |
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Sensory organs of Class Turbellaria
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All or any combo of following:
- statocysts (head position detection) - Auricles (sensory lobes w chemoreceptors) - Ocellli (eyespots) to respond to environmental cues |
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Reproduction of Class Turbellaria
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- Regeneration from separated parts
- TRANSVERSE fission (!) - Sexual, all are monoecious - internal fertilization (not of self) helps to ensure fertilization - eggs laid in cocoons - larvae resemble adults but have time in a swimming stage |
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Class Trematoda
General Characteristics |
- All parasitic & often economically &/or medically important
- Body flat, oval to elongated oval in shape - Outer layer called TEGUMENT is a layer of fused cells (syncytium) really good at both nutrient absorption & resisting the immune defenses of hosts |
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Class Trematoda
Digestive System |
- 2 suckers for attachement, Oral anterior sucker & acetabulum, midbody
- anterior mouth w muscular pumping pharynx that feeds mostly on host cells and cell fragments - GI system divides into 2 blind pouches called CECAE |
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Class Trematoda
Life Cycle |
- 2+ body forms for 2+ hosts, intermediate and definitive (final)
- adults in definitive host live in bloodstream, GI tract, or viscera - eggs via host feces to H2O - hatch, ciliated larva find intermediate host, usu snails, asexually repro - 2nd larval forms exit host, swims til next intermed/final host - may penetrate or be consumed by host |
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Class Cestoidea
General Characteristics |
Tapeworms
- No mouth, digestive tract b/c endoparasite of GI tract, direct absorption - long body made of repeating units called PROGLOTTIDS - 2 main body regions - Scolex - anchoring structure, suckers and/or hooks - neck - immature proglottids - STROBILA - proglottids series that produce eggs at maturity - structurally reduced compared to Turbillaria, Trematoda but MUCH longer |
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Cestoidea
Reproduction |
- Monoecious but released at diff times to assure not self-mating
- + eggs = + organ degeneration - gravid proglottids separate & leave w host feces - eggs consumed by meat sources, which are then passed by eating raw/undercooked meat source |
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Beef/Pork Tapeworms
Cycle and disease epidemiology |
- in pig/cow bloodstream -> muscle & form cysts & become BLADDER WORMS (CYSTERCERCI)
- muscle eaten by humans, cystercerci in human GI can invade muscles, called CYSTERCERCOSIS, potentially fatal |
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Phylum Gastrotrichs
"Gastrotrichs" General Characteristics |
- aquatic
- Complete GI system- mouth, pharynx, intestine, anus - acoelomate as adults |
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Gastrotricha
Reproduction |
- Marine are monoecious, sexual repro
- Freshwater are usually PARTHENOGENETIC - NO larval stage, hatch mini adults |
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Phylum Nemertea
"Proboscis Worm" or "Ribbon Worms" General Characteristics |
- Mostly marine, some freshH2O & terrestrial
- carnivorous on segmented worms & crustaceans - Up to 30m long. Some of longest invertebrates! - + Evolutionarily advanced than flatworms - |
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Phylum Nemertea
General Characteristics II |
- extendible proboscis for feeding, sometimes barb-tipped
- Protonephrida, cerebral ganglion, nerve cords - Primitive coelom like fluid-filled sac - Complete GI tract w anus - Closed blood circ system but no heart; lg vessels contract |
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Phylum Nemertea
Reproduction |
- Dioecious
- External fertilization - Free-swimming, ciliated larvae |
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Phylum Acoelomorpha
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- marine
- mostly carnivorous w few parasits - p much v sm flatworms - some think they're most primitive bilateral animals |
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Phylum Cycliophora
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- Fewer than 10 spp ID'd
- ALL live on mouthparts of lobsters - Likely filter feeders - When lobster molts, dwarf males activeate & mate. - Males are literally just a brain & repro tissue |
