Worms Ch.7 Marine Bio Book Ch.36 Biology Book

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WormsCh.7 Marine Bio BookCh.36 Biology Book

• Developed by Dave Werner
• MATES

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Bilateral Symmetry

• Cut body one way 2 identical halves (fig7.12b,
  p.120)
• (bi two, latus side).
• Orientation includes
• Anterior
• Posterior
• Dorsal
• Ventral

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Symmetry Comparison
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FlatwormsPhylum Platyhelminthes

• Simplest dorsoventrally flattened (flat backs
  bellies)
• triploblastic (composed of three fundamental cell
  layers)
• Real organs organ systems
• no body cavity other than the gut
• Central nervous system simple brain
  (aggregation of nerve cells)
• lack an anus the same pharyngeal opening both
  takes in food and expels waste
• must respire by diffusion, and no cell can be too
  far from the outside, making a flattened shape
  necessary

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Platyhelminthes

• Life without a coelom The image at left is a
  fluke (possibly a species of Probolitrema).
  Flukes, like other parasitic flatworms, have
  complex life cycles often involving two or more
  host organisms. At right, a planarian (Dugesia).
  Planarians are free-living flatworms, and have a
  much simpler life history. They inhabit
  freshwater, and are carnivores (even without
  teeth) or scavengers. Most are less than a
  centimeter long.

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Marine Flatworms

• Marine flatworms The marine flatworms
  (polycladids) are the largest of the free-living
  flatworms, sometimes reaching lengths of 15
  centimeters. Polycladids get their name from
  their highly branched digestive cavity. These
  individuals were photographed on a reef near the
  island of Guam.

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3 Groups of Flatworms

• 1. Class Turbellaria-free-living, include the
  planarian, Dugesia, found in the oceans, fresh
  water, in moist terrestrial habitats, a few are
  parasitic

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• 2. Class Trematoda, or flukes, all parasitic,
  have complex life cycles specialized for
  parasitism in animal tissues. Members of one
  major taxon of flukes, the Digenea -- which
  includes the human lung fluke -- pass through a
  number of juvenile stages that are parasitic in
  one, two, or more intermediate hosts before
  reaching adulthood, at which time they parasitize
  a definitive host.
• Flatworms include non-parasitic worms such as
  planaria, which live in water, and parasitic
  flukes and tapeworms. The human liver fluke
  infects over 75 of the people in parts of Japan,
  China, and South Asia. The adult fluke, about 3/4
  inch long, lives in the bile ducts of the liver
  its eggs (1) pass from the body in the feces. The
  eggs, containing larvae, are eaten by water
  snails (2) and then develop into another form,
  which passes into the water. They then bore into
  the bodies of fishes (3). When raw fish is eaten
  (4) - as is common in the Orient - the young
  worms swim from the intestine into the fine
  branches of the bile duct and grow to maturity.

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• 3. Class Cestoda, or tapeworms, are intestinal
  parasites in vertebrates, and they also show
  anatomical life history modifications for
  parasitism.
• Use suckers or hooks to latch on
• 50 ft worm found in Sperm Whale

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Beef Tapeworm - The cestodes (tapeworms) Taenia
saginata (beef tapeworm) and T. solium (pork
tapeworm).  Taenia solium can also cause
cysticercosis. Life Cycle
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Ribbon WormsPhylum Nemertea

• about 900 known species (fig.7.14, p.121)
• the European nemertine Lineus longissimus has
  been known to reach 30 meters (nearly 100 ft) in
  length,
• Most nemertines are marine
• Proboscis-wraps around the prey, and toxic
  secretions immobilize the prey
• Stylet-piercing barb
• nemertines are carnivorous most feed on small
  invertebrates like crustaceans and annelids, but
  some feed on the eggs of other invertebrates, and
  a few live inside the mantle cavity of molluscs
  and feed on microbes filtered out by the host.
• nemertines have major features that flatworms
  lack, notably a complete gut with an anus, and a
  system of blood vessels. This vessel system may
  in fact be homologous with the coelom, or
  fluid-filled lined body cavity
• True organsw/ organ system central nervous
  system

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Proboscis

• Prostoma rubrum, an example of the phylum
  Nemertea, with its long proboscis everted.
• Fig 7.14, p. 121

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Nematodes - RoundwormsPhylum Nematoda

• Nematodes are the most numerous multicellular
  animals on earth
• Most common in soil marine sediments
• nearly 20,000 described species (gt500,000 total)
• 1,000 somatic cells
• possess digestive, nervous, excretory, and
  reproductive systems, but lack a discrete
  circulatory or respiratory system
• range from 0.3 mm to over 8 meters
• The largest nematode ever observed is
  Placentonema gigantisma, discovered in the
  placenta of a sperm whale w/ 32 ovaries
• Found inhabit intestines of seals dolphins
  flesh of fish (sashimi)
• Humans - hookworm, trichinosis and elephantiasis

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• Intestinal Roundworms, of which Ascaris is a
  common form, infect wild and domestic animals and
  man. Eggs drop to the ground in animal feces.
  Humans are infected by eating contaminated food.
  The diagram at right shows the life history of
  Ascaris. Eggs hatch into larvae in the intestinal
  tract and bore through intestine wall (1). Blood
  carries larvae to lungs (2), where they grow.
  They are then coughed up or crawl up windpipe to
  back of mouth (3), are swallowed (4), and mature
  in intestine (5). A female worm living in the
  intestine may have millions of eggs in its body.
  These pass out in feces (6) and, if eaten by
  other animals, start the life cycle over again.
• Hookworm, once a serious disease in the southern
  U.S., is still common in the warm areas of the
  world. Infected people lack energy. The hook-worm
  life cycle is like that of intestinal roundworms
  except that infection occurs as larvae hatched in
  the warm soil bore through the skin, usually on
  the soles of the feet, to enter the blood.

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Trichina Worm

• Round Worm
• The trichina worm lives inside the small
  intestine of a host animal, where it mates and
  reproduces. Once her eggs have been fertilized,
  the female burrows into the intestinal wall and
  releases her larvae. The larvae migrate into the
  lymph channels of the intestine, from which they
  enter the bloodstream and travel to all parts of
  the body. When the larvae reach the skeletal
  muscles they burrow into the muscles and form
  tough cyst-like cocoons. The host secretes lime
  salts, which are deposited in the capsule,
  eventually transforming the capsule into a
  completely calcified cyst. The worms may live in
  the cyst for years until they are consumed and
  digested by another mammal.

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Nematode Worms

• Marine Nematode - Draconema

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• Here Parborlasia corrugatus worms are eating fish
  eggs. P. corrugatus has a one-way gut with a
  large mouth and a closed circulatory system
  nemertean worms are the simplest animals with a
  circulatory system. Like other proboscis or
  nemertean worms, the wedge-shaped head of P.
  corrugatus has a fluid-filled cavity used to
  rapidly shoot a barbed proboscis which the worm
  uses to capture prey and defend itself 1. This
  harpoon-like proboscis has adhesive secretions
  which secure prey. P. corrugatus is chemically
  defended by an acidic mucus (pH 3.5) which
  potential predators avoid 4.

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Segmented WormsPhylum AnnelidaEverybody's
favorite, worms. . .

• earthworms, leeches, polychaetes
• about 9000 known species
• Segmentation
• Hydrostatic Skeleton
• Coelom
• Cerebral Ganglion

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Polychaete WormsClass Polychaeta

• Mostly marine- 10,000 species
• 2-4 in.
• Proboscis w/ jaws
• Parapodia flattened extensions
• Setae bristles (Fig. 7.15)
• Closed Circulatory System
• Gills w/ capilaries on parapodia body allow
  respiratory exchange

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Polychaete External Anatomy
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Nereis speciesClam or Sand Worm
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More Annelids

• Class Oligochaetes small, live in mud/sand
  (p.273)
• Marine relative of earthworms
• Lack parapodia

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And More Polychaetes

• Leeches (Class Hirudinea) mostly FW, marine
  species are found attached to fish inverts
  (parasitize)
• Sucker at each end w/ no parapodia
• hermaphroditic

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Phylum Pogonophora

• Beard Worms (pogonophorans) lack a mouth and
  gut (fig. 7.17) use symbiotic bacteria to
  manufacture food.
• 4in.-7ft. Read fig.7.17
• Vestimentiferans hydrothermal vent worms

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Crawdad says " Hay-dee ! "

• This is my buddy Crawdad. He lives in a 'holler
  by the crick' near Tahlehquah OK.Those are
  tequila worms in his beard ... kind of a
  rasta-okie thing, I guess.
• He's a trip.
• Whoops! Wrong Picture

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Leeches in the eye of an unfortunate soul who
drank from the wrong pond in India. Probably
Hirudinaria granulosa. - Mark E. Siddall
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Peanut WormsPhylum Sipuncula

• Soft, unsegmented bodies (fig. 7.18, p.124)
• 320 known species
• .4in.-14in.
• Deposit feeders
• Peanut shaped

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EchiuransPhylum Echiura

• Marine
• Look like soft unsegmented sausages buried in
  mud/sand
• Spoon-like or forked proboscis (fig 13.9, p.272)
• Deposit feeders

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