MS130 - Biology
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Pete Markiewicz

Week 03

Multicellularity, Plant and Animal body plans, Life History

THE CELL - THE SMALLEST COMPLETE UNIT OF LIFE

"...Cells are created as information flows through the communication web of millions of large, complex organic molecules"

• History of discovery of the cell
  http://scctv.net/biomedia/pdf/cell/UnitofLife.pdf
• Molecules making up the cell
  http://www.lsic.ucla.edu/classes/mimg/robinson/micro6/m6webnotes/2Cell.html
• Cells under a microscope
  http://biology.nwc.cc.wy.us/biology/b1010lab/b1010lab.htm
• Cell division
  http://www.enchantedlearning.com/subjects/animals/cell/mitosis/label
• Cells in motion (movies)
  http://www.microscopyu.com/moviegallery/livecellimaging/index.html

1. Viruses - a "half alive" entity
(like the hard disk without the computer)
http://micro.magnet.fsu.edu/cells/virus.html

• Require host cells to activate and use the information in their genes
• Outside the cell they are semi-crystaline arrays of DNA or RNA, protected by protein shell
• Parts of cells, rather than ancestors of cells - store information without any ability to process it.

2. Cellular life - complete living systems

• The evolutionary tree of life
  http://tolweb.org/tree/phylogeny.html
  Picture of "deep" evolutionary tree
   
• Bacterial (prokaryote) cell structure
  http://micro.magnet.fsu.edu/cells/bacteriacell.html

• More pictures of bacterial cells
  www.spm.genebee.msu.su/ activity/bactcells.html

• Structure of eukaryotic cell (believed to have resulted from the symbiotic fusion of sevearl prokaryote cells)

Single-celled eukaryotes

• Protozoa or "protists"
  Paramecium in its living state
• 
  Stentor in its living state
  Euglena in its living state
  Amoeba in its living state
  Amoeba videos
  Toxoplasmosis - disease caused by protozoa from cats
   
• Fungal cells
   

  Pictures of fungal cells and hyphae	Candida (fungus, harmful yeast cell) http://www.rkm.com.au/FUNGI/Candida.html

   

• Food yeast (fungus that produce alcohol, make bread rise)
  Brewer's yeast

FUNGI AND BACTERIA AT WORK

• How cheese was invented - The story of Thog and his wife, Thogette
   
• How to make body odor pleasant? Tell them its cheese!
  http://www.livescience.com/humanbiology/050518_words_smell.htm
   
• BACTERIA in your food: Acetobacter aceti (vinegar), Bacillus cereus (cocoa, tofu), Bac. licheniformis (cocoa), Bac. megaterium (cocoa), Bac. pumilus (cocoa), Bac. subtilis (cocoa, rice natto), Erwinia dissolvens (coffee), Lactobacillus acidophilus (acidophilus milk; yogurt), Lact. bulgaricus (yogurt), Lact. casei (many cheeses), Lact. delbrückii (pickles, soy sauce), Lact. helveticus (many cheeses), Lact. lactis (most cheeses), Leuconostoc (many cheeses), Leucon. mesenteroides (pickles; sauerkraut), Pediococcus (sauerkraut, ensilages, pickles), Propionibacterium acidipropionici (Emmenthaler cheese), Prop. freundenreichii (Swiss cheese), Prop. jensenii (buttermilk), Prop. shermanii (Emmental and Swiss cheeses), Prop. technicum (Edam cheese), Prop. thoenii (Emmenthaler cheese), Streptococcus cremoris (many cheeses), Strep. diacetilactis (sour cream, and butter products), Strep. faecalis (pickles), Strep. lactis (many cheeses, sour milk), Strep. thermophilus (yogurt and many cheeses).
   
• Bacteria thrive in hostile human bellies
  http://www.livescience.com/humanbiology/060105_stomach_bacteria.html
   
• FUNGI in your food: Penicillium camemberti (cheese), Pen. roqueforti (cheese), Rhodotorula rubrum (Prisoner-of-War bread [WW2] (degrades cellulose)), and Saccharomyces cerevisiae (baking, alcoholic fermentation), Sacc. uvarum (cider)
   
• Body bugs

• More body bugs
  https://bcrc.bio.umass.edu/phpwiki/index.php/TheMicrobesOnTheBody
  • Babies are born microbe-free. Bacterial inhabitants reach adult levels within 9 days.
  • The total number of bacteria excreted each day by an average adult is 100 billion to 100 trillion (mostly in feces).
  • There are approximately 10 million bacteria on a square cm. of skin
  • There are no known bacteria living in the bladder and the lower portions of the lungs. Bacteria are also not found in the blood, the lymph system, and the nervous system: these areas are generally sterile and if infected, it is a sign of a serious disease
• Americans lie about washing their hands
  http://www.livescience.com/othernews/050921_dirty_hands.html

  Only 75 percent of men washed their hands compared to 90 percent of women Sports fans at Turner Field, particularly the guys, had the worst hand hygiene habits –only 74 percent of all patrons washed their hands (84 percent of the women and 63 percent of the men). Results from the New York train stations provided the biggest gender split – 92 percent of the women washed their hands compared to only 64 percent of the men. San Francisco turned out to be the most hygiene-conscious city in the study – 88 percent of the market goers washed their hands after using the facilities

   

• The war on bacterial is wrongheaded
  "...The rising incidence of asthma and allergies in the developed (cleaner) world, doctors say, could be tied to the relatively sterile environments (e.g. using antibiotics and antibacterial soap) that our children live in compared to a generation ago.  Children not exposed to harmful bacteria, or conversely, given antibiotics to kill bacteria, do not receive the germ workout required to make antibodies..."
  http://www.livescience.com/humanbiology/060328_bad_bacterial.html
   
• Live longer by getting dirty
  http://www.livescience.com/humanbiology/041013_longevity_flies.html
   
• Mycorrhizae - fungal symbiotes with land plants
  http://www.treedictionary.com/DICT2003/shigo/WINTER.html
   
• MOVIE Cordceyps fungi - an "Alien" style parasite which takes over the brain of infected animals before killing them
  http://www.i-am-bored.com/bored_link.cfm?link_id=21052
   
• Extreme (microbial) creatures (USGS)
  http://www.livescience.com/animalworld/050207_extremophiles.html
  • Extreme Life Records (all Eubacteria or Archaebacteria)
  • Hottest: 235 F (113 C) Pyrolobus fumarii (Volcano Island, Italy)
  • Coldest: 5 F (-15 C) Cryptoendoliths (Antarctica)
  • Highest Radiation: (5 MRad, or 5000x what kills humans) Deinococcus radiodurans
    D. radiodurans is a so-called extremophile because it thrives in extreme environments that would kill most organisms, such as radioactive waste dumps and hot springs. While a radiation dose of 10 grays (Gy) would kill a human, D. radiodurans can take up to 5,000 Gy with no visible effect. It can survive heat, cold, vacuum, and acid. It is so resilient scientists nicknamed it "Conan the Bacterium," after the fictional barbarian warrior.
  • Deepest: 3.2 km underground
  • Acid: pH 0.0 (most life is at least factor of 100,000 less acidic) pH 5-8
  • Basic: pH 12.8 (most life is at least factor of 1000 less basic) pH 5-8
  • Longest in space: 6 years Bacillus subtilis (NASA satellite)
  • High Pressure (1200 times atmospheric)
  • Saltiest: 30% salt, or 9 times human blood saltiness. Haloarcula
  • Smallest: <0.1 micron or 500 fit across a human hair width (picoplankton)

PLANT AND ANIMAL CELLS

Plant, animal and multicellular fungal cells evolved sometime around 1 billion years ago from more primitive eukaryotic cells. They represent a very small branch on the big "tree of life". Compared to other organisms, they are specialized for multicellular-life.

• Plant cell structure
  http://micro.magnet.fsu.edu/cells/plantcell.html
  
• Animal cell structure
  http://micro.magnet.fsu.edu/cells/animalcell.html
  
  http://biology.nwc.cc.wy.us/biology/b1010lab/animcell.jpg
• Animal cell structure, forming organelles
  http://www.cartage.org.lb/en/themes/Sciences/Zoology/AnimalPhysiology/Anatomy/AnimalCellStructure/AnimalCellStructure.htm

• Make a jello animal cell
  http://www.enchantedlearning.com/subjects/animals/cell/jello/

MULTICELLULARITY AND TISSUES

• Great debates: the odds of complex (meaning multi-celled) life (many scientists believe that single-celled life may be common in the universe, but multi-celled life may be extremely rare)
  http://www.astrobio.net/news/article239.html
   

• Plant tissues
  http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/P/PlantTissues.html
  http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookPS.html

• Animal tissues
  http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/AnimalTissues.html

EVOLUTION OF MULTI-CELLULARITY

• Animals appear 600-100 million years ago, but tiny colonies
• "Snowball Earth" at 600 million years ago causes "mass extinction"
• First large animal fossils found at end of "Snowball Earth" episode
• Oldest bilaterally symmetrical animals (with a front, back, side) found (575 million years old)
  http://www.usc.edu/uscnews/stories/11494.html
• 3D fossils reveal fractal organization of Edicarian fauna
  http://www.newscientist.com/channel/life/evolution/dn6162
• New information on the "Edicarian" fauna before the Cambrian "explosion" of animal life
  http://www.astrobio.net/news/modules.php?op=modload&name=News&file=article&sid=1650&mode=thread&order=0&thold=0
  Pictures - http://www.ucmp.berkeley.edu/vendian/critters.html
  
  Dickinsonia, an Edicarian animal
   
• Modern eukaryotic kingdoms (appeared about 540 million years ago)
  http://www.ucmp.berkeley.edu/help/taxaform.html

ANIMAL BODY PLANS (PHYLA)

• http://animaldiversity.ummz.umich.edu/site/accounts/information/Animalia.html

Animal body plans and the 9 major animal phyla
http://www.spotsylvania.k12.va.us/bms/tr/9phyla/the%20nine%20major%20animal%20phyla%20homepage.htm

PHYLUM PORIFERA (sponges)
No true tissues, saclike body with a few kinds of differentiated cells, "spicule" external skeleton

• Pictures of sponges - http://animaldiversity.ummz.umich.edu/site/accounts/pictures/Porifera.html
• Morphology - http://www.ucmp.berkeley.edu/porifera/poriferamm.html
• Cross-section showing cellular organization - http://www.enchantedlearning.com/subjects/invertebrates/sponge/labelx/

PHYLUM CNIDARIA (jellyfish, corals)
two tissue layers (outer ectoderm "skin" and inner endoderm "gut"), nematocyst "stingers" muscles, senses, nerve net but no brain

• http://images.google.com/images?q=Cnidaria&hl=en&lr=&sa=N&tab=wi
  http://animaldiversity.ummz.umich.edu/site/accounts/pictures/Cnidaria.html
• Body plans - http://www.mbl.edu/leuckart/L11.GIF
• Box Jellyfish (advanced, predatory jellyfish, deadly poisonous with multiple eyes but no centralized brain)
  http://www.nature.com/news/2005/050509/pf/050509-7_pf.html
  http://bioweb.uwlax.edu/zoolab/Table_of_Contents/Lab-3a/Cubozoa/cubozoa.htm

  

• Stung by jellyfish - http://www.ourdotcom.com/TripLog/MexicoMainland/PuertoVallarta/images/NanAndJoeVisit/Jan20_06_AngAfterBoxJellyfishSting.jpg
• Jellyfish sting gallery - http://www.skinatlas.com/jellyfish2.htm
• Box jellyfish sting - http://www.scuba-doc.com/bjsting.jpg

PHYLUM PLATYHELMENTHES (flatworms)
No internal body cavity, solid internal tissue, bilateral symmetry, nervous system, no heart, kidney, etc. Many are parasitic

• http://animaldiversity.ummz.umich.edu/site/accounts/pictures/Platyhelminthes.html
• http://images.google.com/images?svnum=10&hl=en&lr=&q=Platyhelmenthes
• Schistosomiasis (a nasty fluke with lifecycle like "Alien") - http://www.ecohealth101.org/unbalancing/health/schistosomiasis.html
• Life cycle - http://www.dpd.cdc.gov/dpdx/HTML/Schistosomiasis.asp?body=Frames/S-Z/Schistosomiasis/body_Schistosomiasis_page1.htm
• Person showing reaction to schistosomiasis eggs, liver damage - http://www.path.cam.ac.uk/~schisto/Background/Hep.Splen.Disease.html
  Another bad reaction to the parasite, with liver damage - http://www.afids.org/Case6.jpg
• Tapeworm "hooks" - http://www.okc.cc.ok.us/biologylabs/Documents/Animals/Tapeworms.htm
• Pathogenic flatworms - http://www.medicine.mcgill.ca/tropmed/txt/lecture5%20filaria%20and%20schisto.htm

PHYLUM NEMATODA (roundworms)

 

Free-living soil nematode	Trichinella (infects human muscle) http://biodidac.bio.uottawa.ca/thumbnails/catquery.htm?Kingdom=Animalia&phylum=Nematoda

• http://animaldiversity.ummz.umich.edu/site/accounts/pictures/Nematoda.html
• Roundworm pathology - wow!
  http://curezone.com/image_gallery/parasites/infected/default.asp?i=0&n=15
• Ascaris lumbricodies (infects 25% of the human race worldwide)
  http://ryoko.biosci.ohio-state.edu/~parasite/ascaris.html
• Removing an ascaris VIDEO
  Link here
• Pinworms (infect 10% of human race worldwide) VIDEO
  http://content.nejm.org/cgi/content/full/354/13/e12/DC1

Phylum Mollusca (mollusks)
True coelom, (organs suspended in internal cavity, lined by mesoderm), heart with open/closed circulatory system, muscles, brain, shell protects soft body. Celpalopods have advanced eyes an brains, many species are hermaphrodites (both sexes in one animal)

• http://animaldiversity.ummz.umich.edu/site/accounts/pictures/Mollusca.html
• Anatomy of a mollusk - http://images.encarta.msn.com/xrefmedia/aencmed/targets/illus/ilt/T761279A.gif
• Snails mating - http://www.newport78.freeserve.co.uk/images/snails.jpg
• Sequence of snails mating
• Cephalopods - http://images.google.com/images?svnum=10&hl=en&lr=&q=cephalopods
• Octopus eye - http://www.kasson.com/Solomons94/octeye.htm

PHYLUM ANNELIDA (segmented worms)
Internal body parts repeat in "segements", fuse together to make wormlike animal, closed circulatory system, multiple "brains", no true legs or skeleton

• http://animaldiversity.ummz.umich.edu/site/accounts/pictures/Annelida.html
• Body structure showing segmentation - http://bill.srnr.arizona.edu/classes/182/Annelid.htm
• Marine annelids - http://tolweb.org/tree?group=Annelida&contgroup=Bilateria
• Marine annelid - http://www.dnr.state.sc.us/marine/sertc/images/photo%20gallery/polychaete%20JSL%203465.jpg
• Freshwater leech - http://www.fcps.k12.va.us/StratfordLandingES/Ecology/mpages/freshwater_leech.htm
• Leech on person - http://www.diggerhistory.info/images/asstd/leech.jpg
• Giant (fish) - leech - http://www.molluscan.com/fish/150m/leech.jpg

PHYLUM ARTHROPODA (jointed-foot, insects, crustaceans, and spiders)
Segmented, many segments fused into "head", "thorax", abdomen, complex eyes, and other senses, open circulatory system, external exoskeleton, most successful group of animals on Earth

Praying Mantis (insect)	Spider (arachnid)	Crab (crustacean)
Australian (giant) ant	Dust mite in pillow (arachnid)

• http://animaldiversity.ummz.umich.edu/site/accounts/pictures/Arthropoda.html
  Crustaceans - http://www.dnr.state.sc.us/marine/sertc/gallery.htm
• Internal anatomy - http://images.encarta.msn.com/xrefmedia/aencmed/targets/illus/ilt/T013778A.gif
• Insects - http://www.scienceexperts.com/Cockroach-Madagascar-BPSPP.jpg
• Arachnids (spiders and scorpions) - http://www.uidaho.edu/so-id/entomology/wolf%20spider.jpg
• More spiders - http://www.xs4all.nl/~ednieuw/Spiders/spidhome.htm
• Scorpions - http://www.homegrownherps.com/Spider%20Page/scorpions.htm
• Dust mites in your pillow - http://www.livescience.com/humanbiology/051014_pillow_ecosystem.html
  Forensic entomology -
  http://homepage.eircom.net/~hedgerow4/black-blowfly-03.JPG
  Corpse maggots
  http://www.campbell.k12.ky.us/links/webquest/bug/5N1.jpg
• Maggot therapy
  http://www.ucihs.uci.edu/com/pathology/sherman/home_pg.htm
  Maggots debriding gangene
  http://www.ucihs.uci.edu/com/pathology/sherman/cases.htm
• Parasitic fleas
  http://medent.usyd.edu.au/photos/flea_photos.htm
• "Hairy" crustacean found 1000 miles from Easter Island
  http://www.cnn.com/2006/TECH/science/03/08/furry.lobster.ap/index.html
  
• Arthropods can be "smart" - bees use "legislature-like" consensus-building to find a new hive
  http://www.astrobio.net/news/modules.php?op=modload&name=News&file=article&sid=1935&mode=thread&order=0&thold=0

PHYLUM ECHINODERMATAPhylum (starfish, sea urchins, sea cucumbers)
Internal vascular hydraulic system replaces muscles, very close to chordates in evolution (seen in embryology, a duterostome)

• http://animaldiversity.ummz.umich.edu/site/accounts/pictures/Echinodermata.html
• Several "body plans" for starfish (e.g. brittle stars) - http://www.seashells.org/identcatagories/starfish.htm
• Sea cucumbers and starfish in nature - http://www.richard-seaman.com/Wallpaper/Nature/Underwater/Invertebrates/

Phylum Chordata (chordates, vertebrates)
Internal skeleton, segmented muscles, dorsal spinal cord, closed circulatory system
 

Tuna (Pices)	Mouse (Mammalia)	Naked Social Mole-Rat (Mammalia)	Bird chicks (Aves)
Boa Constrictor (Reptilia)

• http://animaldiversity.ummz.umich.edu/site/accounts/pictures/Chordata.html
   
• Primitive chordates
  How tunicate larvae led to primitive chordate (neoteny) - http://bill.srnr.arizona.edu/classes/182/Chordate/Tunicate.JPG
  Amphioxus - http://record.wustl.edu/2002/04-26-02/worm.html
  Amphioxus lifestyle - http://www.anselm.edu/homepage/jpitocch/genbios/34-04a-LanceletAnatomy-L.gif
   
• Jawless fish
  Lamprey - (jawless vertebrate) - http://www.abc.net.au/science/news/img/environment/lamprey200404.jpg
  Lamprey on fish - http://www.axelfish.uoguelph.ca/research/lamprey-on-fish.GIF
   
• Sharks, skates, and rays (NOT fish, just another animal swimming in water)
  How sharks stay warm-blooded in cold water -
  http://www.livescience.com/imageoftheday/siod_051101.html
   
• Pisces (various kinds of fish)
  Paddlefish - http://www.tnaqua.org/Newsroom/HighRes/paddlefish.jpg
   
• Amphibians
  Salamander - http://www.karstconservancy.org/karst/pictures/cave-salamander.jpg
   
• Reptiles
  Komodo Dragon - http://www.no-pest.com/KomodoDragon.jpg
  Dragon eating food - http://www.dennisprager.com/assets/PragerSnapShots/dragon.jpg
  Komodo dragon eats Sharon Stones' husband's toe - http://film.guardian.co.uk/News_Story/Exclusive/0,,505119,00.html
   
• Dinosauria (NOT REPTILES)
  Velicoraptor (closely related to birds) - http://animals.timduru.org/dirlist/dino/Velociraptor_J01-Dinosaur-Face.jpg
   

  Old reconstruction of Velicoraptor, "lizard-like"	New reconstruction, emphasizing bird-like features
  Ovoraptor - a giant raptor which very bird-like features	Troodon - a large-brained dinosaur with grasping hands and binocular vision (should have been our ancestor!)

  
  Dinosaur fossil gallery - http://www.livescience.com/php/multimedia/imagegallery/igviewer.php?imgid=350&gid=25&index=0
  "Birdlike" dinosaur reconstruction gallery - http://www.livescience.com/bestimg/result.php?back=&cat=avianancestors
  Another feathered dinosaur - http://animals.timduru.org/dirlist/dino/Sinosauropteryx_J01-FeatheredDinosaur.jpg
  
  Advanced lungs (more than ours) in birds and dinosaurs - http://pharyngula.org/index/weblog/comments/dino_lungs/P25/
   

• Pterosaurs (flying animals evolved from reptiles, NOT dinosaurs or birds)
  Pterosaurs - up to 60 foot wingspan - http://www.nzherald.co.nz/section/story.cfm?c_id=2&ObjectID=10344848
  Skeleton of smaller pterosaur (16 feet) - http://www-news.uchicago.edu/releases/03/pterosaur-bandw.jpg
  Compared to human - http://www-news.uchicago.edu/releases/03/pterosaur-teeth.jpg
  http://www-news.uchicago.edu/releases/03/031218.pterosaur.shtml
  Pterosaur picture - http://www-news.uchicago.edu/releases/03/pterosaur-color.jpg
   
• True birds (possibly simply the surviving branch of Dinosauria)
  Archeopteryx - http://www.staabstudios.com/archbig.JPG
  Archeopteryx fossil - http://www.univ-ubs.fr/ecologie/Photos/archeopteryx.jpg
  Owl (Aves, birds) - http://forum.50birds.com/uploads/Byuboy54/2004-10-22_164458_Hooty,-The-Barred-Owl-contest.jpg
   
• Mammals (evolved before birds and dinosaurs, got "their chance" after the asteroid hit 68 million years ago)
  Anteaters (mammals) - http://www.alinereptiles.com/mammals.html
  Squirrel - http://www.kolkatabirds.com/hillbirdsofind/malayangiantsquirrel8nam.jpg
  "Large" (meaning 3 foot long) mammals dined on juvenile dinosaurs during Cretaceous
  http://www.newscientist.com/channel/life/dn6874.html
  Jurassic-era "beaver" find stuns scientists
  http://www.newscientist.com/article.ns?id=dn8769&feedId=online-news_rss20
  Recognition of death, skulls of the deceased by Elephants
  http://www.newscientist.com/article.ns?id=dn8209&feedId=online-news_rss20
   
• Primates - branch of mammals evolved for tree-dwelling
  Monkeys (New World, Old Word) - http://anthro.palomar.edu/primate/prim_4.htm
  Japanese Macques (snow monkey) - http://news.bbc.co.uk/olmedia/1905000/images/_1909335_monkey10.jpg
  Babboon (showing sexual skin) - http://www.medaille.edu/vmacer/120_graphic_15baboonbright.jpg

Lion Tamarin (new world monkey, males raise children)	Capuchin (advanced tool use)

• Great apes (gibbon, gorilla, common chimpanzee, bobobo chimpanzee, orang-utan)
  http://anthro.palomar.edu/primate/prim_7.htm
  Koko (gorilla) - http://www.foamtotem.org/daily/mr400photo2.jpg
  Koko painting - http://the.honoluluadvertiser.com/2000/Oct/01/image2/101localnews17_b.jpg
  Orang-utan - http://nicelytoasted.net/cheese/albums/colchester/Orang.jpg
  Orang baby - http://www.ms-starship.com/sciencenew/images/ORANG_UTAN_BABY_-md34P51716.jpg
  Orang and human child - http://alljames.com/users/sarah/images/chloe%20with%20orang%203.JPG
  Orang washing clothes - http://www.ie.lspace.org/ftp-lspace/images/fan-art/orang-2.jpg
  
  Common Chimp - http://www.game-reserve.com/images/wildlife/primates_other/young_chimp_da.jpg
  Bonobo (Pygmy Chimp) - http://photo.zootrotters.nl/albums/BatchUpload/Dierentuinen/Apenheul/Bonobo1.jpg
  Bonobo sex - http://www.subgenius.com/bigfist/pics2/pics3/apics2/BONOBO!.jpg
  Bonobo upright - http://www.primatesworld.com/images/19980514-bonoboupright.jpg
   
• The "third chimpanzee" or hairless ape - Homo sapiens

  	http://www.purenudism.net/images/full/Free_Nudist_Image_Weekly_26.jpg
  http://www.zwoje-scrolls.com/shoah/n13.jpg

   

Creating believable aliens - http://www.sff.net/people/mmolvray/aliens.htm

Some good quotes:

"...One eye is good; two eyes are even better because they can provide wide angle vision or depth perception; three eyes are deadly. More is not better....Up to a point, organs enhance a creature's ability to survive, but anything beyond that point is just one more thing to have accidents with. That is why we don't see creatures with extra eyes or arms running around, and that is why anything that does have extras feels alien. It does not, however, feel real.

"...The amount of energy generated in an oxygen-based, or aerobic, metabolism is eighteen times greater than the closest runner-up. We actually have carbon-breathers and sulfur-metabolizers right here on Earth. They're all single cells. Insufficient energy is produced to support a multicellular slime mold, to say nothing of an intelligent being capable of creating an alphabet. ..."

"...Another method, (for having sex) practiced by plants, is to alternate generations. Adults do not simply produce offspring. Adults, in effect, produce proto-eggs and proto-sperm. These grow to form complete multicellular individuals that sometimes resemble the adult and sometimes, as in the case of moss, are quite different. The proto-egg and proto-sperm individuals then produce the actual eggs and sperm that fuse to form a new adult. This isn't quite the same as having more than two sexes, but it's certainly strange from a mammalian perspective."

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