Bell work1. Take out your bell work.2. On the next line, write today’s date.3. On the next line (or lines), copy today’s bell work questions (below).4. After writing the questions, write your answer in complete sentences.5. After we review the answer to today’s question, correct your answer if needed, and place your bell work into your folder. We will use the same sheet of paper all week. All bell work from this week must be on one sheet of paper. Bell work will be collected on Friday.

Define radial symmetry.

Date 11/8/13 Subject ZoologyBenchmarks SC.912.L.15.1 Bell work Define radial

symmetry.

Objective Distinguish the major organs of an echinoderm

Agenda • Echinoderm direct instruction

• Echinoderm notes

Essential Question

What structures are specific to echinoderms?

Vocabulary radial symmetry, central disk, radial canal, madeporite

Ticket Out: Notes completion

Homework: NONE

Bell work

Define radial symmetry.

• Symmetry around a central axis

GENERAL CHARACTERISTICS

• Ex: sea stars, brittle stars, sand dollars, sea urchins, & sea cucumbers

• All marine

• “Spiny-Skinned Animals”

• Radial Symmetry as adults – 5 parts

• Regenerate = Autotomy

GENERAL MORPHOLOGY

• A. INTERNAL SKELETON of Calcareous ossicles (plates)

• Variations :

Brittle / Sea Stars – many small plates that move with one another

Sea Urchin & Sand Dollar – skeleton plates fused into shell called “test”

Sea Cucumber – degenerated & buried in leathery body

B. Water Vascular System

• Network of canals – run throughout body ending w/tube feet

• Varying internal water pressure can extend or contract tube feet

• Tube feet end in small suction cups

• Used in locomotion, food capture, & respiration

C.• Mouth on oral surface

(bottom / ventral)

• Anus on aboral surface (top / dorsal)

ECHINODERM TYPES

SEA STARS• 5 Arms / Rays 4 – 10”

• Prey on bivalves (clams, mussels) & coral

• Many eat w/stomach outside body; pop stomach out mouth

Body Plan

• 2 – 4 rows of tube feet on each ray extend from ambulacral groove

• Have pedicellariae or tiny, forceps-like structures on aboral surf. to pick up & remove dirt

Water Vascular System• Water enters

madreporite on aboral surface into a short, straight stone canal

• Stone canal connects to circular canal around the mouth = ring canal.

• Enters five radial canals extending down each arm

Water Vascular System

• Radial canals carry water to hundreds of paired tube feet.

• Bulb-like sacs or ampulla on tube feet contract & create suction

Other Body Systems

• No circulatory, excretory, or respiratory systems

• No head or brain

• Eyespots on the tips of each arm detect light

Reproduction

• Separate sexes

• External fertilization

• Females produce 200,000,000 eggs / season; meroplankton

BRITTLE STARS

• Most mobile; fast

• Snake-like movement

• Disc .4 – 1.2 “; arms 2 – 2.4 “

• Scavengers

• In largest class (with basket stars)

• Arms break off readily

BRITTLE STAR LARVA

SEA CUCUMBERS

• Lack arms & visible spines; elongated

• Flexible, leathery body

• Burrowers

• 5 rows of tube feet run length of body

• 10-30 modified tube feet form tentacles

around mouth

• Tentacles have sticky ends to trap plankton; or eat detritus

• Breathes through anus

• Eject internal organs to scare predators (evisceration) ; regenerate in days

• Symbiosis with Pearl Fish which lives in its anus.

• Feed on gonads by day

• Filter Feeders

• Can detach & move around

Sea lilies & feather stars

Sea Urchins

• Spines for protection, moving, trapping food

• Shell = test• Divided into 10 sections

• 5 Ambulacral w/tube feet• 5 Interambulacral without

• Covered w/muscle & skin to help mobility

• Tube feet – moving, capturing food

• Pedicellarea – cleaning & defense

• Aristotle’s Lantern – 5 teeth together like bird’s beak; to scrape algae from rocks

Sand Dollars • Flattened version of urchin

• Live in sand along coastlines

• Food falls between dense spines & carried to mouth by cilia & tube feet

        

• Tiny, moveable spines for burrowing

• Aristotle’s Lantern

Sea Biscuits

• Not as flat as dollars

• Live in sand along coastlines;

burrow• Tube feet for respiration• Pedicellarea• Eat detritus in sand   • Short dense spines for

movement cover test

What’s next

• Echinoderm notes, on Moodle

• Write your answers on paper for inclusion with your folder.

Friday 11/8 – Staple folder assignments together in the following order:

• Bell work

• Distinguishing Arthropods (Monday)

• Grasshopper Dissection (Tuesday)

• Spider Classification (Wednesday)

• Parasite Reading Comprehension (Thursday)

• Echinoderm Notes (Friday)

• Homework – Arthropod Review