Homework from last Homework from last class:class:Complete the Phylum Facebook project

Read Ch. 29-1 Echinodermata

Phylum Phylum Echinodermata:Echinodermata:EchinodermsEchinodermsChapter 29:Echinodermatapp. 637-644

BBC Life: Time Lapse of Sea BBC Life: Time Lapse of Sea StarsStars http://www.youtube.com/watch?

v=HG17TsgV_qI

Phylum Echinodermata - echino = “spiny”, dermis = “skin”

Radial symmetry (often pentaradial)o However, larvae have bilateral symmetry

3 cell layers (ectoderm, endoderm, mesoderm)

Internal skeleton (endoskeleton) – plates of CaCO3

Water vascular system with tube feet

All marine

Very ancient group unlike those of any other living group

Introduction to Introduction to EchinodermsEchinoderms

Echinoderms appear to be related to chordates (vertebrates).

Scientists think this because:

1.Echinoderm larvae are similar to certain chordate larvae.

2.Echinoderms have an endoskeleton (not exoskeleton).

3.Their pattern of embryonic development is same as for chordates (radial cleavage – anus develops before mouth)

◦ Mollusk, annelid, and arthropod embryos undergo spiral cleavage - mouth develops first.

Classes of EchinodermsClasses of Echinoderms1) Class Asteroidea: ex: star fish (aka sea stars)• Often pentaradial, usually predatory• Creep along using tube feet

2) Class Ophuroidea: ex: brittle stars• Largest group• Often pentaradial• Filter feeders or detritus feeders• Flexible arms

3) Class Echinoidea: ex: sea urchins, sand dollars• Some with protective spines• Usually grazers (eat algae)

Classes of EchinodermsClasses of Echinoderms4) Class Holothuroidea: ex: sea cucumbers• Usually detritus feeders (aka scavengers)• Radial symmetry• Often live in ‘herds’ on ocean floor

5) Class Crinoidea: ex: sea lilies and feather stars• Long, feathery arms• Sessile• Filter feeders• Rare today but lots of fossils of them

Form and Function of Form and Function of EchinodermsEchinodermsRepresentative member: sea star

Digestive system:• Starfish pry open prey (ex: bivalves) with their tube

feet, then flip stomach inside out into the prey and secrete enzymes to digest the tissue. Then they suck their stomach back in.

oral surface (location of mouth) is on bottom

aboral surface (location of anus) is on top

Scavengers (ex: sea cucumbers)

Filter feeders (ex. sea lillies)

Respiratory system: Tube feet for O2/CO2

exchange Some species have

“skin gills”

Circulatory and Excretory systems: No separate systems for these (tube feet and skin gills

are all over the body and take care of O2/CO2 exchange and metabolic waste removal

Nutrients (food) are distributed by digestive glands, not by blood (there is no blood)

Sea star tube feet

Adult sea star internal anatomy

Nervous system: Primitive No head Nerve ring surrounds mouth; radial nerves in

arms Sea stars have eyespots at tip of each arm Statocysts (to tell which side is up)

Musculoskeletal system:

• Instead of muscles, sea stars have a unique water vascular system (hydraulics)

• Water vascular system consists of:ring canal: forms a circle around digestive system

radial canals: canals which extend into each arm

tube feet: suction-cuplike structures connected to the water vascular system

madreporite (sieve plate): opening used to filter water into the water vascular system

(see p. 639)

• Sea star endoskeleton is composed of protective plates made of CaCO3 (for protection, not involved in movement).

• Some echinoderms can walk around on their arms (ex: brittle stars) or crawl (ex. sea cucumbers)

Reproductive system:• Usually separate sexes

• “Broadcast method” - sexual reproduction

• Regeneration – asexual reproduction

• Many species can regrow lost parts

Sea Star Renegerationhttp://www.youtube.com/watch?v=f7cXeWxxfD4

Sea stars control many populations (they are important predators)

Sea urchins often control algae populations

Both sea stars and sea urchins have been known to upset the ecology of an area

Sea urchins are used in embryological research (large eggs)

Drug research (ex. anti-viral and anti-cancer drugs)

Some are edible delicacies (ex. sea urchin eggs and sea cucumbers)

Ecology of EchinodermsEcology of Echinoderms

Demo – Sea Star Dissection

Homework for next class:Homework for next class: Complete Echinoderms and Chordates Worksheet –

1st side only (Section 29-1)

Complete sea star colouring diagram (include a key)

Work on 15 Ch. 29 Echinodermata cue cards

◦ Due Thursday, April 21 (Ch. 26-29 Invertebrate Test day)

Have a great

weekend!

Works CitedWorks CitedImages taken from the following

sources:http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/bio%20102/bio%20102%20lectures/animal%20diversity/protostomes/lophotrochozoans/lophotrochozoans.htm

http://myfishtanks.info/fish-profile/saltwater-invertebrate-profiles/brittle-star-tiger-striped-serpent-seastar/

http://www.iloverubberstamps.com/catalogpage2.html

http://clipart.usscouts.org/library/us_fish_and_wildlife_service/fish/

http://jklsciencelab.weebly.com/starfish-dissection.html

http://www.topnews.in/law/general/featured?page=5816&destination=taxonomy

http://www.easyvectors.com/browse/other/sea-cucumber-clip-art

http://etc.usf.edu/clipart/49800/49826/49826_sea_lily.htm

http://www.australiascoralcoast.com/en/Things_to_see_and_do/Nature_and_wildlife/Pages/Nature_and_wildlife.aspx

http://www.picassomio.es/crown-of-thorns-starfish-poster-2386298.html

http://en.wikipedia.org/wiki/File:Sea_urchin_tests.jpg

Works CitedWorks CitedImages taken from the following

sources:http://www.kadamsphoto.com/nature_recreation/seashells_mollusks.htm

http://www.interesting-facts.biz/category/marine-animals-facts/page/3

http://megashare.info/watch-the-office-season-7-episode-14-online-TWpVM01nPT0

http://aspire.mlml.calstate.edu/aspire04/updates/nov/25nov/nov25.htm

http://siera104.com/bio/echin.html

http://www.naturebridge.org/headlands/blog/rachel-loud/creature-month-sea-stars

http://bonneeats.com/?p=270

http://www.mahingakai.org.nz/mahinga-kai-species/kina