What makes it a Fungus?
My main focus for today was explaining the Three Questions that scientists ask to determine whether something is Plant, Animal, or Fungus (we studied Microbiology in Science Club last year, so we aren't focusing on Protists, Eubacteria, or Archaebacteria right now). Then we looked back at their questions about Mosses and Lichens and answered them (Mosses are a no, Lichens are a yes).
1) review (for students who did this lesson as part of the Human Body several years ago) the
"Building an Organism" activity
Cut five slips of paper and label them as follows:
Cell
Tissue
Organ
Organ System
Organism
Place one single Lego by the slip of paper that says Cell.
Connect several Legos together. Place your creation by the slip of paper that says Tissue.
Create several Tissue creations, each made of several Legos. Attach your Tissues to one another. Place this by the slip of paper that says Organ.
Create several Organ creations, each made of several Tissues, each made of several Legos. Attach your Organs to one another. Place this by the slip of paper that says Organ System.
Create several Organ Systems, each made of several Organs, each made of several Tissues, each made of several Legos. Attach your Organ Systems to one another. Place this by the slip of paper that says Organism.
2) notice that the word part "organ" is repeated often in the terminology, introduce the term "organelle," explain that the Lego-cells themselves have to be made up of smaller parts, draw a picture of an animal cell (which does not have a cell wall) and a plant cell (which does)
3) explain that
the initial system of classification was mainly based upon morphological characteristics -- looking at something's outside features -- but now scientists look inside the organism in order to group like with like
Question #1 - Does it have a cell wall?
if yes, it may be a Plant or Fungi
if no, it is an Animal
Question #2 - Does it contain chitin?
if yes, it may be an Animal (exoskeleton) or Fungi (in the cell wall)
if no, it is a Plant
Question #3 - Can it do photosynthesis?
if yes, it may be a Plant or Lichenized Fungi
if no, it is an Animal
4) note how astonishing it is that Fungi are the only thing here that can potentially say YES to all three of those questions, and explain that scientists are very curious as to where it falls within the sequence of evolution and the Tree of Life!
a few various interesting things we discussed:
Fungi are closer to Animals than they are to Plants
LUCA (Last Universal Common Ancestor)
Lichens consist of Fungi in partnership with either green or blue-green algae, so scientists had to decide where to classify them; ultimately, they decided to categorize them by their Fungal partner, so therefore they are considered part of the Fungi Kingdom
more primitive designs tend to be ancient organisms (for example, mosses have spores and they are older than the flowering plants which have seeds)
Nature doesn't waste a good idea BUT it wouldn't makes sense for Plants and Animals to branch off from one another first and then Plants have an offshoot which is Fungi (using chitin in the cell wall) and then for chitin to evolve independently later on in the Animal branch... where we see chitin as part of the design of some of its very first organims, the invertebrates
the skeleton of a black coral has chitin
chitin is also found in the most primitive vertebrates, the cartilaginous fishes
if chitin didn't evolve in two completely different places in the Tree of Life, did Plants evolve first (with cell walls) and then Fungi (decomposers would have had to have something to eat, so they couldn't have been first?) with cell walls with chitin and then Animals branched off from Fungi and kept the chitin but moved it to an external structure instead of an internal structure?
Animals have internal digestion (we have organs and organ systems for that) but Fungi have external digestion
"Generally, plants make their food using the sun's energy (photosynthesis), while animals eat, then internally digest, their food. Fungi do neither: their mycelium grows into or around the food source, secretes enzymes that digest the food externally, and the mycelium then absorbs the digested nutrients." - Ministry of Forests
inter-plant communication through mycorrhizal networks
watch a portion of Wild Isles, episode 2, "Woodlands" (38:10 - 42:20)
wetware computers
Fungi are often just stuck off to one corner in an illustration of the Tree of Life, but really the question of where they go is tremendously important and interesting! (a nice illustration which does include Fungi is found in Grandmother Fish: A Child's First Book of Evolution by Jonathan Tweet)
We ended the session by doing the wonderful Tree of Life work by Waseca Biomes. Always a favorite, this time we slowed down and read all of the Fungi cards instead of zooming past them to hone in on Plants or Animals.
Waseca Biomes Tree of Life Material - 69 Leaves
list of organisms
The Fact File cards we read were:
card 1 - Prokaryotes
card 6 - Protists
card 11 - Protista: Slime Molds
card 13 - Kingdom Fungi
card 14 - Kingdom Fungi: Phylum Zygomycota
card 15 - Kingdom Fungi: Phylum Zygomycota
LEAF 6 - bread mold
Rhizopus nigricans
card 16 - Kingdom Fungi: Phylum Ascomycota
card 17 - Kingdom Fungi: Phylum Ascomycota
LEAF 7 - reindeer lichen
Cladonia rangiferina
card 18 - Kingdom Fungi: Phylum Basidiomycota
card 19 - Kingdom Fungi: Phylum Basidiomycota
LEAF 8 - fly amanita
Amanita muscaria
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