Invertebrate Zoology Notes

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  • Topic: Annelid, Phylum, Cnidaria
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AP Biology, Chapter 33
Invertebrates [by clade]

SUMMARY
INTRODUCTION

PARAZOA
Introduction
Phylum Porifera: Sponges are sessile with porous bodies and choanocytes
1. Identify the parts of a sponge (including the spongocoel, porocyte, epidermis,
choanocyte, mesohyl, amoebocyte, osculum, and spicule) and describe the function of
each.
a. Lifestyle: sessile, immobile filter feeders
b. Water circulation
i. Epidermis seals outside
ii. Flagellated choanocytes lining the spongocoel push water toward the
osculum
iii. As water is sucked in the porocytes, the choanocytes filter suspended
particles
c. Nutrition: amoebocytes distribute digested particles
d. Structure
i. Mesohyl contains protein matrix and spicules
ii. Constructed and maintained by amoebocytes
e. Reproduction
i. Sexual: most are hermaphrodites
ii. Asexual: regeneration

RADIATA
Introduction
Phylum Cnidaria: Cnidarians have radial symmetry, a gastrovascular cavity, and
cnidocytes
2. List the characteristics of the phylum Cnidaria that distinguish it from the other animal
phyla.
a. Have muscle and nerve tissue, lack well-developed mesoderm
b. Radially symmetrical; mouth but no anus
c. Carnivores and detritovores: cnidocytes paralyze and attach to prey
d. Prey digested in dead end gastrovascular cavity
e. Reproduce sexually, by budding, and by regeneration
3. Describe the two basic body plans in Cnidaria and their role in Cnidarian life cycles.
a. Polyp
i. Sessile, mouth up, surrounded by tentacles
ii. Ex.: Hydra, sea anemone
b. Mudusa
i. Free-swimming, mouth down
ii. Ex.: jellyfish
4. List the three classes of Cnidaria and distinguish among them based on life cycle and
morphological characteristics.
a. Class Hydrozoa: ex. Hydra; alternate polyp and medusa
b. Class Scyphozoa; ex. jellyfish like Aurelia; dominant medusa
c. Class Anthozoa: ex. anemones; polyps only
Phylum Ctenophora: Comb jellies possess rows of ciliary plates and cohesive
colloblasts
5. List the characteristics of the phylum Ctenophora that distinguish it from the other
animal phyla.
a. "Comb-bearer"; eight rows of fused cilia for locomotion
b. Two long tentacles have colloblasts for feeding on plankton

PROTOSTOMIA: LOPHOTROCOZOA
Introduction
6. Distinguish between the following pairs: acoelomates and coelomates, protostomes
and deuterostomes, and Lophotrochozoa and Ecdysozoa.
a. Acoelomates lack a body cavity; coelomates have a body cavity surrounded by
mesoderm
b. Protosomes have spiral determinate cleavage, schizocoely, and "first mouth";
vs. radial, indeterminate, enterocoely, and "first anus"
c. Ecdysozoa are the molting protostomes; Lophotrochozoa are the other
protostomes
Phylum Platyhelminthes: Flatworms are dorsoventrally flattened acoelomates
7. List the characteristics of the phylum Platyhelminthes that distinguish it from the other
animal phyla.
a. Acoelomate without an anus
b. Name means "flat worms"
c. Both parasitic and free-living forms
8. Distinguish among the four classes of Platyhelminthes and give examples of each.
a. Class Turbellaria
i. Most marine, some freshwater, predators and scavengers; body
surface ciliated
ii. Ex.: planaria
b. Class Monogenea
i. Parasites (flukes) with a simple life history, one egg one adult
ii. Aquatic ectoparasites
c. Class Trematoda
i. Vertebrate parasites with two suckers and complex life histories
ii. Schistosoma
d. Class Cestoidea
i. Scolex with suckers and hooks; proglottids are reproductive sections;
no digestive system
ii. Tapeworms
9. Describe the generalized life cycle of a trematode and give an example of one fluke
that parasitizes humans.
a. Life cycle
i. Sexual reproduction in human, eggs shed in feces...
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