2. ๏ฝ Asexual: regeneration/fragmentation
๏ฝ โFragmentation is a self-produced,
mechanical breaking of the organism into two
or more pieces, followed by regenerative
growth of missing parts in each fragment.โ
3. ๏ฝ Hermaphroditic: contain both female and male
organs, produces both sperm & eggs
๏ฝ exchange of sperm occurs between two worms
๏ฝ Mature sperm and egg cells are
deposited in cocoons produced
by the clitellum
๏ฝ ova (eggs) are fertilized by the
sperm cells within the cocoon
๏ฝ The cocoon slips off the worm
and is deposited in or on the soil.
The eggs hatch after about 3 weeks.
http://edis.ifas.ufl.edu/IN047
4. ๏ฝ Eggs hatch within 2-3 weeks if conditions are
favorable
๏ฝ An average of 4 worms are
produced from each
cocoon
๏ฝ Worms can reproduce
after 12 months
5. ๏ฝ The nervous system of the earthworm is "segmented"
just like the rest of the body.
๏ฝ No true "brain" , but cerebral ganglia (dense bundles
of nerves) are located at the anterior (head) end
๏ฝ If these cerebral ganglia are removed, the earthworm
will move continuously.
๏ฝ Each segment has a ganglion which controls only
that segment
๏ฝ Earthworms have touch, light, vibration and chemical
receptors all along the entire body surface.
6. ๏ฝ Most earthworms are scavengers that feed on
dead organic matter.
๏ฝ nourishment is extracted from
soil or leaves as they pass through
the gut (digestive sys)
๏ฝ Note: does not require highly developed sense
organs (such as eyes, which would be of little use
underground) or food-catching structures
๏ฝ http://www.austmus.gov.au/factSheets/earthworms.htm
7. ๏ฝ urea (a nitrogenous waste product) is excreted
through long tubules called nephridia
๏ฝ Part of these wastes are
picked up from body
tissues and the blood
๏ฝ The urea is expelled through
the pores of the nephridia
๏ฝ Earthworms leave a trail of
this expelled urea called
โcasingsโ which are full of
nutrients
8. ๏ฝ Circulation occurs through a series of closed
vessels.
๏ฝ The two main vessels, pumping structures, are the
dorsal and ventral blood vessels. Although some say that they
have 5 โhearts,โ they are not true hearts.
๏ฝ Capillary beds branch off the main vessels to pick
up or release nutrients and, oxygen
9. ๏ฝ 1st Food particles taken in by heterotrophs
are broken down by digestive enzymes into
smaller building blocks usually by hydrolysis
reactions (breaking apart by H2O).
โฆ Carbohydrates glucose
โฆ Proteins amino acids
โฆ Fats fatty acids, glycerol
โฆ Nucleic acids nucleotides (n-base, sugar,
phosphate)
10. ๏ฝ 2nd These building blocks are then
synthesized into the large molecules needed
by the cell usually through dehydration
reactions (linking together by the removal of H2O).
โฆ Glucose + glucose carbohydrates
โฆ Amino acid + amino acid proteins
โฆ Fatty acids + glycerol fats, lipids
โฆ Nucleotide + nucleotide nucleic acids
11. ๏ฝ Moist skin is the respiratory organ of the
earthworm
๏ฝ Oxygen and carbon dioxide simply diffuse
through the skin.
