digestion in animals – part 1
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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. - PowerPoint PPT PresentationTRANSCRIPT
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 & food
Water & waste
Collar cellEpidermal cell
Collar cell
Spicule
Incurrent pore
amebocyte
flagellum
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
egg
larva
polyp
Polyp body form
Hydra on water plants
Hydra Anatomymouth
tentacles
bud Gastrovascular
cavity
Basal disc
ovary
testis
•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 – the only highly developed system is its reproductive system – hermaphroditic
Digestion– absorbs host’s already digested food.
Scolex – head with hooks and suckers
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 of feet
– Larvae in human feces
– Causes fatigue – may cause physical and mental retardation if children have it
• Trichina– From
undercooked pork
– Causes severe muscle aches when larvae migrate from 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 dirtEats blood
Earthworm Anatomy
Earthworm eats dirt • Pathway of food :Mouth pharynx esophagus crop gizzard intestine anus 1 2 3 4 5 6 7
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6
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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
slug
slug
clam
snail
squid
octopus
Digestion in Mollusks
Clams:Mucus-feedersTrap food in Mucus on gillsThen swallowsBoth 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,
spiders
scorpion
Dust mites tick
Class Crustacea – two body regions = cephalothorax
most live in water
Millipedes and Centipedes
The endThe end