Invertebrates

Page
1

Slide 1

What function do the red whorls of this organism have?

Slide 2

Life Without a Backbone

Invertebrates are animals that lack a backbone.

They account for 95% of known animal species.

Slide 3

Fig. 33-2 Review of Animal Phylogeny

ANCESTRAL

PROTIST

Common

ancestor of

all animals

Calcarea

and Silicea

Eumetazoa

Bilateria

Cnidaria

Lophotrochozoa

Ecdysozoa

Deuterostomia

Slide 4

Fig. 33-3-1 Invertebrate Diversity

Calcarea and Silicea (5,500 species)

A sponge

Cnidaria (10,000 species)

A jelly

Acoela (400 species)

Acoel flatworms (LM)

1.5 mm

LOPHOTROCHOZOANS

Platyhelminthes (20,000 species)

A marine flatworm

Ectoprocta (4,500 species)

Ectoprocts

A brachiopod

Brachiopoda (335 species)

Rotifera (1,800 species)

A rotifer (LM)

A ctenophore, or comb jelly

Ctenophora (100 species)

A placozoan (LM)

0.5 mm

Placozoa (1 species)

Slide 5

Concept 33.1: Sponges are basal animals that lack true tissues

Sponges are sedentary animals from the phyla Calcarea and Silicea.

They live in both fresh and marine waters.

Sponges lack true tissues and organs.

Slide 6

Fig. 33-UN1

Calcarea and Silicea

Cnidaria

Lophotrochozoa

Ecdysozoa

Deuterostomia

Slide 7

Sponges are suspension feeders - capturing food particles suspended in the water that pass through their body.

Choanocytes, flagellated collar cells, generate a water current through the sponge and ingest suspended food.

Water is drawn through pores into a cavity called the spongocoel, and out through an opening called the osculum.

Slide 8

Anatomy of a Sponge

Azure vase sponge (Callyspongia

plicifera)

Spongocoel

Osculum

Pore

Epidermis

Water

flow

Mesohyl

Choanocyte

Flagellum

Collar

Food particles

in mucus

Choanocyte

Amoebocyte

Phagocytosis of

food particles

Spicules

Amoebocytes

Slide 9

Sponges consist of a noncellular mesohyl layer between two cell layers.

Amoebocytes are found in the mesohyl and play roles in digestion and structure.