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.

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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


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

Collar cell

Epidermal cell

Water & food

flagellum

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


JELLYFISH - MEDUSAS


Hydra

Hydroid

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 – 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


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

Some are parasitic to humans

  • Filaria

    • Causes elephantiasis

    • No treatment

    • Carried by mosquitoes


This lesion is caused by a nematode infestation


Elephantiasis

  • 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


LeechEarthworm

Eats dirt

Eats blood


Earthworm Anatomy


Earthworm eats dirt

  • Pathway of food :

    Mouth pharynx esophagus crop gizzard intestine anus

    1 2 3 4 5 6 7

7

6

1

5

4

3

2


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

octopus

slug


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,

scorpion

tick

Dust mites

spiders


Class Crustacea – two body regions = cephalothoraxmost live in water


Millipedes and Centipedes


The end

The end


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