Invertebrates

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Portion of

a colony

of polyps

1 mm

Key

Haploid (n)

Diploid (2n)

Slide 20

Fig. 33-8-2

Feeding

polyp

Reproductive

polyp

Medusa

bud

Medusa

ASEXUAL

REPRODUCTION

(BUDDING)

Portion of

a colony

of polyps

1 mm

Key

Haploid (n)

Diploid (2n)

Gonad

SEXUAL

REPRODUCTION

MEIOSIS

FERTILIZATION

Egg

Sperm

Zygote

Slide 21

Fig. 33-8-3

Feeding

polyp

Reproductive

polyp

Medusa

bud

Medusa

ASEXUAL

REPRODUCTION

(BUDDING)

Portion of

a colony

of polyps

1 mm

Key

Haploid (n)

Diploid (2n)

Gonad

SEXUAL

REPRODUCTION

MEIOSIS

FERTILIZATION

Egg

Sperm

Zygote

Planula

(larva)

Developing

polyp

Mature

polyp

Slide 22

Scyphozoans

In the class Scyphozoa, jellies (medusae) are the prevalent form of the life cycle

Slide 23

Cubozoans

In the class Cubozoa, which includes box jellies and sea wasps, the medusa is box-shaped and has complex eyes.

Cubozoans often have highly toxic cnidocytes.

Slide 24

Anthozoans

Class Anthozoa includes the corals and sea anemones, which occur only as polyps.

Slide 25

Concept 33.3: Lophotrochozoans, a clade identified by molecular data, have the widest range of animal body forms

Bilaterian animals have bilateral symmetry and triploblastic development.

The clade Bilateria contains Lophotrochozoa, Ecdysozoa, and Deuterostomia.

Slide 26

Fig. 33-UN3 Lophotrochozoa includes the flatworms, rotifers, ectoprocts, brachiopods, molluscs, and annelids

Calcarea and Silicea

Cnidaria

Lophotrochozoa

Ecdysozoa

Deuterostomia

Slide 27

Flatworms

Members of phylum Platyhelminthes live in marine, freshwater, and damp terrestrial habitats.

Although flatworms undergo triploblastic development, they are acoelomates.

They are flattened dorsoventrally and have a gastrovascular cavity.

Gas exchange takes place across the surface, and protonephridia regulate the osmotic balance.

Slide 28

Flatworms are divided into four classes: