Upload
msoonscience
View
2.001
Download
2
Tags:
Embed Size (px)
DESCRIPTION
Ch 27 Mollusks and Annelidspp. 594-600
Citation preview
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