427 7 th Grade Agenda Collect HW Workbook

4/27 - 7 th Grade Agenda üCollect HW: Workbook 201 – 204 üEarth Worm üVideo: Walking w/ Dinosaurs üTextbook Reading 428 – 432 üHW: Workbook 205 – 206

How do Earthworms Mate? • Earthworms are hermaphroditic meaning each worm has organs of both sexes. • One worm has to find another worm in order to mate

Do earthworms have eyes? • They do not have eyes • But they do possess light- and touchsensitive organs (receptor cells) to distinguish differences in light intensity and to feel vibrations in the ground.

What is the "bump" in the middle of the earthworm? • The bump is the clitellum. • It contains the gland cells which secrete a slimy material (mucus) to form the cocoon which will hold the worm embryos.

Earthworm Cocoons

Can earthworms regenerate themselves? • Yes, but only the front or head end of the earthworm will survive and the amputated tail portion will die.

Virtual Dissection of Earthworm

What is the difference between front end and back end? Front End (Anterior) Back End (Posterior)

What is the difference between top side and bottom side? Top side (Dorsal) Bottom side (Ventral)

Dissecting the earthworm

Internal View

Aortic Arches (Primitive Heart)

Cross section view

Does earthworm have bilateral or radial symmetry? • Bilateral Symmetry

What some common What are Mollusks properties of these animals? • Mollusks are invertebrates with soft unsegmented bodies that are often protected by hard outer shells

Three major groups of mollusks • Gastropods (Single Shell) • Bivalves (Two Shells) • Cephalopods (Mollusks with tentacles)

Comparing Mollusks

Do Mollusks have Open or Closed Circulatory System? • Mollusks have Open Circulatory System: Blood is not always in blood vessels

What are Gastropods? Gastro = “stomach” Pod = “Foot” • Gastropods are both herbivores and carnivores

Earthworm Videos • How Earthworms Move & digest: Worm 7[1]. asf • Aquatic Earthworms: aquaticearthworm 01 ob_t 1[1]. wmv