Transcript Digestive Systems in Animals

-Heterotrophs cannot produce their own food and
must consume other organisms to obtain energyyielding food
- animals use a wide variety of processes and
behaviours to search for, process, and take in their
food
Feeding Mechanisms
-Despite different shapes, sizes, and diets, ALL
animals obtain food through one of the four
feeding mechanisms
- the feeding device (ex. Mouth) can usually tell
you what kind of a feeder an organism is
Feeding Mechanisms
1. Filter Feeders
- aquatic animals
- use a filtering body structure to gather organisms in
surrounding water
- feeder siphons water into mouth and filters out small
organisms to digest (ex. protists, bacteria, larvae)
Eg. Tube sponge, flamingos, clams, barnacles,
whales
Feeding Mechanisms
2. Substrate Feeders
-Live in or on their food source and eat their way through it
Eg. Caterpillars (eat through tissues of leaves),
worms (ingest soil particles with decayed material as
they go)
Feeding Mechanisms
3. Fluid Feeders
-Suck or lick nutrient-rich fluids from live plants or animals
- mouth parts are adapted to pierce or rip skin or leaf tissue
- mouth parts suck or lick blood or sap in their food
Eg. Mosquitoes, ticks, aphids, spiders, bees, butterflies,
hummingbirds, vampire bats
Feeding Mechanisms
4. Bulk Feeders
-Includes most vertebrates
- ingest fairly large pieces of food and sometimes swallow
it whole
- can use tentacles, pincers, claws, fangs, jaws, or teeth to
kill, tear pieces off, or take in mouthfuls of their food
Eg. Humans, great blue heron
Stages of Food Processing
-Nutrients from food must get into individual cells
of an animal’s body in a usable form
- the essential function of an animal’s digestive
system is to break food down into small, soluble
pieces that can pass through cell membranes
- food is broken down into useful substances that
can be absorbed into the circulatory system, and
transported to individual cells
Stages of Food Processing
There are four stages of digesting food:
1) Ingestion – Food is taken in or eaten.
2) Digestion – Food is broken down by mechanical and chemical
processes into molecules small enough for the body to absorb.
3) Absorption – Products of digestion are transported from the
digestive system into the circulatory system. The circulatory system the
distributes the products to the rest of the body.
4) Elimination – Undigested solid waste matter is removed from
the body.
Alimentary Canal - a digestive tract consisting of a long
open tube, with a mouth on one end to ingest
food, and an anus on the other end to
eliminate waste
- Processes food as it moves along the canal
with different organs
- AKA the Digestive Tract
Eathworms have very simple digestive tracts.
Gastrovascular Cavity Feeding
Simple organisms like hydra have a sac-like digestive
system, called grastrovascular systems.
• their mouth and anus are the same.
• pouch lined with digestive cells that secrete enzymes
• does not allow for a digestive stages of a tube
• less efficient, quicker.
Eg. Flatworms, jellyfish
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Cellular Digestion
-used by simple organisms
-Cells engulf food and allow it to penetrate membrane
- can be stored in vacuole or used for energy right away
- food is broken down by enzymes that the cell releases