Homework from last Homework from last class:class:Complete squid lab handout and analysis

questions

Read Ch. 27-2 Annelids

Read over class notes and check out the class blog: http://msoonscience.blogspot.com/

Phylum Annelida:Phylum Annelida:AnnelidsAnnelidsChapter 27: Mollusks and Annelidspp. 594-600

Top 10 Bloodsuckers: LeechTop 10 Bloodsuckers: Leechhttp://www.youtube.com/watch?

v=jMci6O--1wY

Introduction to AnnelidsIntroduction to Annelids• Phylum Annelida – Latin annellus = “little ring”

• Segmented worms

• Bilateral symmetry

• 3 cell layers (ectoderm, endoderm, mesoderm)

• Simplest phylum to have a coelom (fluid-filled cavity lined by mesoderm cells)

• Annelids are considered to be related to mollusks because their larvae are similar (trochophore larvae) and they share similar developmental patterns• Mollusks and annelids likely share a common

ancestor (possibly worm-like)

Comparative cross-sections:

NematodeAnnelid

CoelomCoelom

Pseudocoelom(fluid-filled

space)

endoderm

mesoderm

ectoderm

Coelom (fluid-filled space totally

surrounded by mesoderm)

Most animals have tissues that are derived from 3 embryonic cell layers:Ectoderm: develops into epidermis, ie. skinMesoderm: develops into muscle tissue and mesentaryEndoderm: develops into the tissue of the digestive tract ie. gut

CoelomCoelom

ectoderm

mesoderm

endoderm

The coelom is an important evolutionary advancement:

a)Separates the intestine from the muscles of the body wall by allowing for independent movement

b)Provides a space for a true circulatory system to develop

c)Coelomic fluid circulates O2/CO2, nutrients, and waste

*Mollusks also have a coelom but theirs surrounds only the heart not the entire intestine and internal organs.*

CoelomCoelom

Classes of AnnelidsClasses of Annelids1) Class Polychaeta• Bristly marine worms• Have paired appendages on each

segment

Example members: sea mouse (p. 599)

2) Class Oligochaeta• Earthworms• Terrestrial; fertilize and aerate soil

(produce “castings”

Example members: earthworms, tubifex worms

Classes of AnnelidsClasses of Annelids3) Class Hirudinea Leeches Mostly freshwater Have suckers at both ends;

anticoagulants and anaesthetics to help suck blood

Example members: leeches

Form and Function of Form and Function of AnnelidsAnnelidsearthworm = representative annelidDigestive system: •Complete digestive tract (mouth anus)

• Mouth, pharynx, esophagus, crop (for storage), gizzard (for grinding), intestine, anus

Earthworm digestive system

Respiratory system: • Some aquatic ones have gills• Many (e.g. earthworms) exchange O2/CO2

through the skin

Circulatory system:• Closed circulatory system – blood is

always contained inside vessels• Have primitive “hearts” (earthworms

have 5) to pump blood

Excretory system: • Nephridia (primitive kidneys) in each

segment remove metabolic waste (nitrogen-containing wastes like NH3)

Nervous system:• Fairly well-developed• Have a small brain, eyes or eyespots,

statocysts, sensory tentacles, chemical receptors

Musculoskeletal system:• Longitudinal and circular muscles work

together to propel worm (peristalsis)

• Bristles present on ventral side for grip

Ecology of AnnelidsEcology of AnnelidsEarthworms are very important on land – they

condition soil in 2 ways:

1) Add nitrogen to the soil (in their “castings”)

2) They aerate the soil so oxygen gets in

• In ocean, annelids are often the bottom of food web.

Activity – Song, Story,

Rap, or Poem!Serenade

me!!

Activity Instructions:Activity Instructions:With a partner or working individually, create a song, story, rap, or poem that incorporates 10 characteristics or structural attributes and functions about Phylum Annelida.

Have fun with it!

*Note: If you choose a song, you must write down the tune that goes with your song.*

Homework for next class:Homework for next class:Finish your Phylum Annelida song, story, rap,

or poem (must submit with evaluation sheet)

Complete Annelida question worksheet

Complete earthworm colouring diagram

◦ You must include a key. Example:

Excretory system

Circulatory system

Read over class notes and check out the class blog: http://msoonscience.blogspot.com/

Works CitedWorks CitedImages taken from the following sources:http://www.talktalk.co.uk/reference/encyclopaedia/hutchinson/m0019261.htmlhttp://picasaweb.google.com/lh/photo/M8MUN49EaXJGCYd0AJEgWQhttp://www.biologyjunction.com/earthworm_dissection.htmhttp://www.myfishfinder.com/fishing_forum/index.php?topic=5973.0http://flyguys.net/Leech.htmlhttp://commons.wikimedia.org/wiki/File:Annelida_Hirudinea_Leech_3.JPGhttp://universe-review.ca/R10-33-anatomy.htm

Works CitedWorks Citedhttp://hubpages.com/hub/EarthwormAfraidSaltshttp://www.tutorvista.com/biology/earth-worm-

nervous-systemhttp://robinsonlibrary.com/science/zoology/

invertebrates/annelida/oligochaeta/earthworm.htm

http://www.tutornext.com/help/locomotion-in-earthworm

http://www.neighborhoodnotes.com/news/2010/11/vermicultureworm_ranching_is_all_the_rage/

http://producersconsumers.wikispaces.com/11http://waynesword.palomar.edu/trnov01.htmhttp://www.fotosearch.com/clip-art/

earthworm.html