Download Aquatic Worms - Bowie Aquatic Science

Aquatic Worms
Phylums:
Platyhelminthes
Annelida
General Characteristics of Worms
• Long, slender soft bodies
• Bilateral Symmetry
• Classified according to the shapes of their
bodies
– Phylum Platyhelminthes--flatworms
– Phylum Nematoda--roundworms
– Phylum Annelida--segmented worms
– Phylum Nemertea--ribbon worms
Phylum Platyhelminthes
a.k.a. Flat Worms
Phylum Platyhelminthes
• Dorsoventrally flattened- flat back and belly
• Simplest animals that contain tissues and
organ systems
• Acoelomates: no body cavity
• Triploblastic: three fundamental cell layers
– Epidermis
– Mesoderm (parenchyma tissue), which becomes
muscle tissue
– Gastrodermis
Nervous System
– Auricle: used to
sense surroundings
– Eyespot: cluster of
light-sensitive cells
– Ganglia: cluster of
nerves that send
impulses along two
ventral nerve cords
to the rest of the
body; found near
eyespots (primitive
brain)
– Ladder-like nerve
cord
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Digestive System
– Sac-like: one opening; mouth/anus
– Intestines distribute food
throughout the body
Other Systems
• No circulatory or respiratory system:
– Their flat thin bodies allow diffusion to occur
through skin and cells
• Excretory system:
– Flame cells connected to excretory ducts
http://io.uwinnipeg.ca/~simmons/lb6pg6.htm
Phylum Platyhelminthes
• Both aquatic (freshwater and marine) and
parasitic species
• Classes:
– Turbellaria (flatworms)
– Trematoda (flukes)
– Cestoda (tapeworms)
Class Turbellaria
• Most are free-living carnivores
–Some eat detritus, others eat algae
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Most are marine
Some have toxins for protection
Exhibit warning coloration
Characterized by beautiful colors and
patterns, many have frilly edges
Class Turbellaria
Class Turbellaria
• Movement:
– Benthic: glides along the bottom using well
developed muscles and cilia
– No skeletal system
• Reproductive system:
– Asexual
• stretch its body and break in half; each half can regenerate
– Sexual
• Hermaphroditic--have both sets of gonads and ducts
• Internal fertilization, but NOT self-fertilization
• Exchange of egg and sperm from different organisms must
occur
Class Turbellaria
Class Turbellaria
Planaria
• Can you see the eyespots and intestines?
Phylum Annelida
Phylum Annelida
a.k.a. Segmented worms
• Segmentation: body consists of similar
compartments (rings of an earthworm)
• Triploblastic
• Found in freshwater, saltwater and soil
• Coelomates; coelom: fluid filled cavity that
surrounds the gut and serves as the
hydrostatic skeleton
Phylum Annelida
• Digestive system:
– Complete, one way
• Circulatory system:
– Closed (blood does not leave the vessels)
– Hemoglobin: binds oxygen
• Respiration:
– Gills in some species
– Diffusion across epidermis is most
• Excretory system:
– One pair of nephridia per segment (nephridia is an organ =
to our kidneys)
– Removes waste from coelom and bloodstream
Phylum Annelida
• Muscular system:
– Circular and longitudinal muscles
• Nervous system:
– Pair of cerebral ganglia (brain) connected to a nerve cord that
extends the length of the body
– Ventral nerve cord is connected to lateral nerves in each
segment
– Has sensory cells for touch, taste and perception of light
• Reproductive system:
– Can have separate sexes or can have both sex organs
– Some species can reproduce asexually by budding
Classes of the Phylum Annelida
• Class Polychaeta
– Almost all marine annelids are in this class
– Each body segment has a pair of flattened
extensions, parapodia, with setae (bristles)
– Name means many bristled worms
Class Polychaeta
• Nereis: sandworm
• Carnivore
• Proboscis and jaws to capture prey
Class Polychaeta
• Fanworms and Feather-duster worms
• Feathery tentacles covered with cilia used to
filter feed
• Tubes are made from calcium carbonate or
bits of particles semented together with
mucus
Class Polychaeta
Tube worms
Class Polychaeta
Riftia pachyptila Giant Tube Worms
Giant Tube Worm
Vestimentiferans
Class Polychaeta
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Giant tube worms: Vestimentiferans
Live near hydrothermal vents
3 meters in length (10 ft)
Bright red tentacles contain hemoglobin
No mouth, stomach or gut
Symbiotic bacteria perform chemosynthesis
and provide nutrition to the worm.
Class Polychaeta
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Hesionidae
Onuphidae
Eurythoe complanata
Class Polychaeta
• Tomopteris
– A bioluminescent polychaete
– Lives in abyssal environments
– When attacked, they release luminescent particles
from their legs to confuse the predator and get
away unnoticed
Class Polychaeta
• Chaetopterus pugaporcinus Yes, it means pig butt worm!
• Lives in abyssal environments
• This species is so new...they don’t know if this is the
adult or larval stage...but they haven’t found sex
organs yet...what do you think?
Ecological/ Environmental Niche
•Polychaetes help bring nutrients buried in the
ocean bottom back to the surface
•Consume organic matter unavailable to larger
consumers
•Major food source for invertebrates and
vertebrates