Lecture 11- Protosomes Flashcards
Discuss the basic body plan of each phylum discussed, as well as the features that
distinguish the given phylum from other animal phyla. For each phyla, describe how its members feed and carryout digestion; how they carry
out gas exchange and circulation; whether they have a nervous system; how they
move; and any other distinguishing features.
make a chart
From a diagram, identify the parts of a sponge (including the spongocoel, porocyte,
epidermis, choanocyte, mesohyl, amoebocyte, and osculum) and describe the function
of each structure.
look on slide
Describe the two basic body forms in phylum Cnidaria.
1) Sessile polyp (e.g., anemones)
• Cylindrical, adheres to substrate.
• Tentacles that extend from around the mouth/anus.
2) Floating Medusa (jellies)
• Flattened, mouth-down versions of polyps.
• The tentacles dangle from around the mouth/anus, which points downward.
Describe how cnidarians capture food and the specialized cells that are invovled.
Cnidocytes
• Contain cnidae
• Organelles that explode outwards
Nematocysts
• Specialized cnidae.
• Contain a stinging capsule with a coiled, barbed thread.
• When stimulated, shoots out, puncturing and injecting poison into prey.
• Some are instead sticky function to entangle prey.
List the four classes of Cnidaria and distinguish among them based on body form, providing examples.
1) hydrozoans: Alternate between polyp and
medusa in lifecycle. • Include hydras and PMOW.
2) Scyphozoans (jellies) Medusa is
prominent stage; some have a polyp stage
3) Cubozoan (sea wasp)
Box jellies
• Sea wasp is one of deadliest organisms
known! Sting can kill you in minutes!
4) Anthozoan (sea anemone)
Polyps only.
• Some corals secrete calcium carbonate external
skeleton –> reefs.
(also look at images from slide show)
Distinguish among the 3 classes of Platyhelminthes discussed and give examples of each.
- Turbellaria: free-living (example Bipalium kewense)
- Cestoda: endoparasitic( tapeworms )
- Trematoda: endo or ecto parasitic( flukes)
Describe (in brief) the generalized life cycle of a trematode and/or tapeworm
eggs laid in feces, which infects the vegetation that either pigs or cattle ingest, onocospheres develop in the muscles and then humans are infected by ingesting raw or undercooked infected meat
Describe (in brief) the generalized life cycle of a trematode and/or tapeworm
tape worms lack a digestive tract because they live inside of the digestive tract of their hosts and allow the host to digest food first and then tape worm can absorb nutrients
Describe a rotifer and how they carry out reproduction via parthenogenesis.
• Tiny animals that inhabit freshwater, marine, and damp soil habitats.
Undergo parthenogenesis
• Asexual process
• Offspring (more females!) develop from unfertilized diploid eggs.
• No males required…except when the pond dries up.
• When conditions deteriorate, produce unfertilized haploid eggs.
• Eggs left unfertilized develop into degenerate males.
• Cannot feed themselves.
• Only live long enough to fertilize other haploid eggs.
• Zygote that results forms thick shell (survives dry conditions).
• When conditions improve, zygote breaks dormancy and develops into a new female generation.
Describe the basic body plan of a mollusc and explain how it has been modified in the
Bivalvia, Cephalopoda, Gastropoda, and Polyplacophora, providing examples for each
subphylum.
Body plan: Triploblastic, bilateral symmetry, coelomate (reduced)
1. Polyplacophora (chitons)
• Distinctive feature:
• Eight dorsal plates for protection, no head.
- Gastropoda (snails, slugs, limpets)
• Distinctive features:
• Torsion
• Visceral mass rotates during development –> anus above head.
• Single spiral cone or flattened shell; absent in some.
• Distinct head, eyes at tips of tentacles
3) Bivalvia (clams, oysters, mussels, scallops) • Distinctive features: • Shell divided in two halves. • No distinct head; no radula. • Some have eyes around edge of mantle
4) . Cephalopoda (Octopuses, squid, cuttlefish, nautiluses)
• Distinctive features:
• Shell reduced and internal in squid and cuttlefish; absent in octopuses.
• Foot modified into siphon and part of tentacles.
• Only molluscs with closed circulatory system –> Why? Advantage?
• Complex brain and sensory organs.
• Ink sac – used to confuse predators.
• Can change color – and quickly!
Distinguish between the 4 mollusc subphyla in regards to movement and feeding.
- Polyplacophora: (chitens)
Movement: Cling to rocks in intertidal zone using muscular foot.
Feeding: Graze on algae.
2) Gastropoda (snails, slugs, limpets)
Movement: Cilia or rippling motion of foot.
Feeding: Graze on algae or predate other molluscs.
3) Bivalvia (clams, oysters, mussels, scallops)
Movement: Sessile species secrete strong
threads that tether them to rocks, boats, docks…etc.
• Clams burrow in mud using foot.
• Scallops swim by flapping shells and
jetting water out of mantle cavity.
Feeding:
Suspension feeders
4) Cephalopoda (Octopuses, squid, cuttlefish, nautiluses)
Movement: By firing water out of siphon.
Feeding:
• Active predators
• Tentacles with suckers.
• Beak-like jaws.
• Some have poison saliva.
Distinguish between an open and a closed circulatory system.
The cardiovascular systems of humans are closed, meaning that the blood never leaves the network of blood vessels. In contrast, oxygen and nutrients diffuse across the blood vessel layers and enters interstitial fluid, which carries oxygen and nutrients to the target cells, and carbon dioxide and wastes in the opposite direction. The other component of the circulatory system, the lymphatic system, is not closed.
The open circulatory system is an arrangement of internal transport present in many animals such as molluscs and arthropods, in which fluid (called hemolymph) in a cavity called the hemocoel bathes the organs directly with oxygen and nutrients and there is no distinction between blood and interstitial fluid; this combined fluid is called hemolymph or haemolymph. Muscular movements by the animal during locomotion can facilitate hemolymph movement, but diverting flow from one area to another is limited. When the heart relaxes, blood is drawn back toward the heart through open-ended pores
Compare the circulatory system of molluscs and arthropods.
Mollusca have Open circulation (EXCEPT in cephalopods = closed system).
• Heart pumps hemolymph through vessels into sinuses (open fluid-filled body spaces).
Arthropods: Open circulatory system
• Evolved independently from mollusc system.
• Contains hemocyanin to transport oxygen EXCEPT in insects: tracheal system in insects
delivers gases directly to tissues.
Distinguish among the three classes of Annelida and give examples of each.
1) Oligochaeta – e.g., earthworms
• Terrestrial + aquatic
• Distinguishing characteristic:
• Chaetae present, but sparse; no parapodia.
2) Polychaetes
• Marine - some planktonic, some crawl, some
burrow or live in tubes.
• Distinguishing characteristic:
• Parapodia on each segment; chaetae (bristles) on parapodia.
3) Hirudinea
• Mostly freshwater, some marine and terrestrial.
• Distinguishing characteristics:
• Segmented, but septa often absent.
• Body usually flattened.
• Chaetae absent.
• Suckers on anterior and posterior ends.
Describe the adaptations that enable some leeches to feed on blood.
Parasites temporarily attach to host.
• Use blade-like jaws to slit hole in host’s skin
or secrete enzymes to digest a hole.
• Secrete anesthetic and hirudin (prevents
blood clotting).
• Can consume 10x body weight in blood!!
