animal reproduction sexual & asexual by diana l. duckworth rustburg high school campbell county
TRANSCRIPT
Asexual Reproduction
• Budding – small part of parent’s body grows into new organism
Genetically identical clones
http://johnson.emcs.net/life/images/anemone.bmp
http://www.microscope-microscope.org/gallery/Mark-Simmons/images/hydra2.jpg
Asexual Reproduction
• Regeneration – parent separates into two or more pieces & each piece forms new organism– In some instances
just a new part grows– Sponges, sea stars,
jellyfish, planaria– Also be clones
http://www.starfish.ch/reef/echinoderms.html
Asexual Reproduction
• Parthenogenesis – growth & development of embryo without fertilization by male
• Population all female
Many insects; lizards, salamanders, fish, turkeys
http://www.nova.edu/ocean/ghri/bbc_virginshark.html
Sexual Reproduction – gametes from opposite sexes unite
• Species with sexual reproduction are said to be dioecous – separate sexes
• Often exhibit distinct sexual dimorphism – males and females look different
• Sperm (male gamete) formed by meiosis in testes
• Eggs (female gamete) formed by meiosis in the ovary
http://civilliberty.about.com/od/historyprofiles/ss/news080406_2.htm
Mating• Mating – male &
female join together to ensure fertilization; not essential to sexual reproduction
http://www.hickerphoto.com/elephants-mating-205-pictures.htm
http://www.torreypine.org/animals/reptiles.htmlhttp://www.eeb.cornell.edu/agrawal/photos/milkweed%20fauna/pages/Tetraopes%20tetrophthalmus%20mating.html
http://www.snakesandfrogs.com/scra/lizards/greenanole.htm
External Fertilization
• Males & females release sperm & eggs into the environment – sperm & egg join outside the body– Males & females may
come into close proximity– Eggs & larvae develop
outside the body– Many gametes produced;
many zygotes formed– Usually aquatic
http://www.biol.andrews.edu/everglades/organisms/Invertebrates/marine_inverts/Arthropoda/Atlantic%20Horseshoe%20Crab/atlantic_horsehoe_index.htm
External Fertilization – e.g. Salmon
http://www.mass.gov/dfwele/dfw/dfwstksl.htm
http://escoberphoto.com/travel/katmai.html
http://www.biology-blog.com/blogs/archives/Biology-blog/520525028-Feb-14-2008.html
Internal fertilization
• Joining of sperm & egg inside the body after mating– Ensures selection of mate (not random);
promotes diversity – Parents protect and care for young– Does not require water; can occur on land– Less sex cells produced; increases probability of
successful reproduction– Common in birds, reptiles & mammals
Internal fertilization; external development
• After fertilization, larvae (embryo) are released & development occurs outside female body
• Example: Barnacles
http://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-uk.org.uk/mag/artjan99/barnac.html
http://getfile.ucoz.com/load/9-1-0-578
Internal fertilization & development
• Females put large amounts of energy into development of embryo – very few in litter or clutch – different schemes
• Eggs in “shell” are laid and either abandoned or nurtured in nest
http://www.nps.gov/pais/naturescience/reptiles.htm
http://crd.dnr.state.ga.us/content/displaycontent.asp?txtDocument=542
http://www.fws.gov/archiecarr/photos/index.html
Various levels of parental care
http://animals.nationalgeographic.com/animals/photos/baby-animals/american-crocodile-baby_image.html
http://www.flmnh.ufl.edu/cnhc/potm-mar99.html
Internal fertilization & internal development of eggs; followed by live birth
http://earth-advocates.org/index.php?option=com_content&task=blogcategory&id=22&Itemid=46
http://www.pacfish.org/sharkcon/documents/gruber.html
Internal fertilization, internal development of embryo to fetus, live birth
http://www.abc.net.au/science/scribblygum/march2006/
http://www.seahorse-australia.com.au/pages/seahr_biology.html
In seahorses, eggs are deposited in the malewhere they are fertilized and develop. Babiesborn live.
In most species, it is the female who carries the developing fetus to birth…
http://www.scienceclarified.com/El-Ex/Embryo-and-Embryonic-Development.html
http://www.sciencedaily.com/releases/2008/04/080410184336.htm
http://humangenetics.suite101.com/article.cfm/three_parent_embryo_mtdna
Hermaphrodites
• Organisms that change sex in order to reproduce
Crepidula fornicata – a snail
http://www.opalesurfcasting.net/la_faune_aquatique/la_crepidule_-_crepidula_fornicata_article1202.html?var_recherche=+bar
http://www.dkimages.com/discover/Home/Animals/Invertebrates/Molluscs/Gastropods/Marine-Snails/Crepidulidae/Atlantic-Slipper/Atlantic-Slipper-1.html