C. Digestive
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Transcript C. Digestive
Digestive System
Digestive System - basic plan
Mouth (toothed jaws, oral valves)
Oral cavity (vomerine, palatine teeth, tongue w/
teeth)
Pharynx (pharyngeal tooth pads, gill arches/rakers)
Esophagus (gullet)
Stomach
Digestive System - basic plan
Pylorus (pyloric valve, pyloric caeca)
Small intestine (ducts bring in bile, pancreatic
secretions)
Large intestine/cloaca
Anus
Variation based on diet, lifestyle
Mouth & Oral Cavity
Teeth in Jaws
Food generally
swallowed whole
Teeth used for
capture, not
chewing
Pharynx - gill rakers
Gill rakers
Gill rakers on
anterior side of each
gill arch - prevent
escape of prey
Gill filaments on
posterior side of
each gill arch
Size and shape of rakers depend on
types of foods eaten
Short, blunt gill rakers
Large prey
QuickTime™ and a
decompressor
are needed to see this picture.
Long, fine gill rakers
Particle or
suspension feeder
Developmental changes
Gill rakers can
change in form as
fish develops
Paddlefish - suspension feeder
Long, fine gill rakers
to strain plankton
from water column
Zooplankton’s view!
Pharyngeal teeth
Pharyngeal Teeth
Variety of teeth in
the same general
region
Derived from gill
arches
Feeding
Pharyngeal teeth
Aid oral teeth in
holding “prey”,
directing them into
esophagus
Modified for
crushing, grinding,
shearing of foods
Pharyngeal Teeth
Present in many herbivores that eat plants,
algae, and/or phytoplankton
E.g., Grass carp
Esophagus & stomach
Structure varies with diet
Simple tube to blind-sac, elastic pouch
Pylorus
Pyloric caeca
Pyloric valve controls release of stomach contents
Ray-finned fishes peculiar among vertebrates
Possess numerous pyloric caeca - digestive/secretory glands
Intestines
Carnivore intestines
Intestine usually very short in carnivores
Animal foods digested, absorbed easily
Herbivore intestines
Intestine usually very long in herbivores,
detritivores
Plant foods digested, absorbed slowly
Chondrichthyes
Shark digestive system
Spiral valve in sharks
Increases food passage time through intestine
- improves absorption
Typhlosole in lampreys
Flap of tissue extending
into lumen of intestine
-increases surface area
for absorption
Disclaimer - this is a
picture of an earthworm,
not a lamprey
Circulatory System
Fish have a singleloop circulatory
system
Typical pathway
Heart to gills to
body, back to heart
Major vessels run along (ventral to) vertebral
column
Branches to organs, muscles (segmental)
Heart
Fish have a 2chambered heart
Lungfish Circulatory System
Lungfish have added
features
Lungfish Circulatory System