Download Digestion in Animals – Part 1

Digestion in Animals – Part 1
All Living things get food
somehow
• Most unicellular organisms, like bacteria,
secrete enzymes and absorb nutrients.
• However, In the Protist Kingdom,
unicellular organisms are very specialized
to obtain food.
– Ingestive heterotrophs or autotrophs
Amoeba
Paramecium structure
Oral groove
euglena
Fungi Kingdom
• Secrete enzymes then absorb nutrients –
decomposers. Absorptive Heterotrophs
Animal Kingdom
• There is an increasingly complex system
that allows animals to obtain nutrients from
food.
• Ingestive heterotrophs
All animals eat; all animals
poop (eliminate undigestible
material)!
Simple animals have simple
methods of getting and using
food
• Porifera: filter feeder – no digestive system
Water & waste
amebocyte
Epidermal cell
Collar cell
flagellum
Water & food
Collar cell
Spicule
Incurrent
pore
food
nucleus
Phylum Cnidaria
(formerly called Coelenterata)
• All have stinging cells (cnidocytes)
• Two body forms:
– Medusa – like a jelly fish
– Polyp – like a hydra
• Radial symmetry
• Have tentacles
Cnidarian Cnidocyte
Have you ever been stung by jellyfish?
Cnidarian Life Cycle – medusa and
polyp alternate
medusa
polyp
egg
larva
Polyp body form
Hydra on water plants
Hydra Anatomy
mouth
tentacles
testis
bud
Gastrovascular
cavity
ovary
Basal disc
•Digestion in cnidarians
Extracellular – occurs In
gastrovascular cavity
- enzymes are released from cells
lining cavity and food is digested
within the cavity.
- Nutrients are absorbed by cells
in cavity and waste is expelled
out the mouth (yuch!).
Coral is actually a colony of polyps, most of which are the size
of a single hydra – they just make a case around them for their
home.
Here are a variety of anemones – polyp body form
Phylum - Platyhelminthes
• Have flat bodies
• Some are parasitic
• Most are free-living
These are free-living flatworms
Planaria
Tapeworms – the ultimate parasite – Scolex – head with hooks and suckers
the only highly developed system is its
reproductive system – hermaphroditic
Digestion– absorbs host’s
already digested food.
Phylum Nematoda - roundworms
• Body rounded
• Tube-within-a-tube body format
• Mouth – digestive tube – anus –more efficient –
can have specialized organs along the way
• Most free-living
• Some parasitic
Look like threads
in the microscope
Some are parasitic to humans
• Hookworm
– Enters through soles
• Trichina
of feet
– From
– Larvae in human
undercooked
feces
pork
– Causes fatigue –
– Causes severe
may cause physical
muscle aches
and mental
when larvae
retardation if
migrate from
children have it
intestine to
muscles
• Filaria
•Causes
elephantiasis
•No treatment
•Carried by
mosquitoes
This lesion is caused by a nematode infestation
-Caused by filaria – the worm blocks the
lympatic vessels and the area swells
with lymph.
No treatment is available
(except amputation)
Phylum Annelida
•
•
•
•
•
Segmented worms
Includes earthworms and leeches
Most are free-living
Complex body with organ systems
hermaphroditic
Leech
Earthworm
Eats blood
Eats dirt
Earthworm
Anatomy
Earthworm eats dirt
• Pathway of food :
Mouth
1
pharynx
2
esophagus crop gizzard intestine
3
4
5
6
7
6
5
4
3
2
1
anus
7
Earthworm help the
environment by:
• Adding nutrients to soil
• Aerating soil
• Helping get rid of dead organic
matter
Phylum Mollusca
• Soft-bodied animals
• All have the same kind of larva
• Three types
– Gastropods – stomach-footed
• Snails and slugs
– Cephalopods – head-footed
• Octopus and squid
– Pelecypods – hatchet-footed
• Clams, mussels, oysters, scallops
snail
slug
squid
clam
slug
octopus
Digestion in Mollusks
Clams:
Mucus-feeders
Trap food in
Mucus on gills
Then swallows
Both food and
mucus
Octopus and squid catch live prey using
their tentacles and eat them
Snails scrape food off surfaces
using their radula
Phylum Echinodermata
• Spiny skinned animal
– Starfish
– Sand dollar
– Sea cucumber
• Turn stomach inside out to eat – stomach gives off
digestive juices and the digested mess is swallowed
along with the stomach when it is brought back into the
body.
• Radial symmetry – no head, tail, front or back
• Move using tube feet – part of water vascular system
Sea urchins, sand dollars,
and starfish
Phylum Arthropoda
•Jointed legs
•Chitinous exoskeleton
•Ventral nerve cord
•Must molt to grow
•Some undergo metamorphosis
•Includes insects, crustaceans, spiders,
millipedes and centipedes, and horseshoe crabs
Class Insecta
•Six legs
•May have wings
•Undergo metamorphosis
•Varied mouthparts
•Breathe using spiracles
Some common insects
Some of these are
insects, some are not….
Can you tell which is
which?
Class Arachnida –
8 legs, no antennae,
simple eyes, chelicerae,
tick
scorpion
Dust mites
spiders
Class Crustacea –
two body regions = cephalothorax
most live in water
Millipedes and Centipedes
The end
The end