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BSC 201L (14e)
Lab #3: Radiate Animals
Use the text and figures in Exercise 8 (The Radiate Animals) to aid your study of the prepared
slides and preserved specimens; examine the additional specimens as indicated.
Things to know for Phylum Cnidaria:
Polyp or medusa? (or both?)
Solitary or colo nial?
Marine water (MW) or fresh water (FW)?
Structures and their functions
Phylum Cnidaria - 5 classes; we will look at 3
Class Hydrozoa, hydroids and hydromedusae
โ both polyp and medusa (dimorphism) typically present and o f similar size (small)
โ medusae have a velum
โ solitary or colonial
โ most are MW species; but all FW cnidarian species are in this class
Hydra โ text pp. 122-125
โ FW
โ solitary polyp only (no medusa stage)
โ rings of cnidocytes on tentacles
1. Budding slide โ Fig. 8-2
โ a type of asexual reproduction
โ LABELS: tentacles, mouth, and bud
2. Slide (x.s.)
โ LABELS: epidermis and gastrodermis
Obelia โ text pp. 125-127
โ MW
โ colonial polyps and solitary medusae
3. Polyps slide โ Fig. 8-3
4. Medusa slide โ Fig. 8-3
Gonionemus โ text pp.127-129
โ MW
โ solitary medusoid form only (no attached polyp stage)
5. hydromedusa โ Fig. 8-4
โ LABEL: velum (tentacles have been removed on the specimen, to better see it)
โ one of the largest hydromedusae
Physalia, Portuguese Man-of-War
โ MW
โ colonial polyps with attached medusae
โ pneumatophore: float/air bladder (modified zooid)
6. Preserved polymorphic colony
