Transcript Protists 1 - How Biology Works

Pond Water
Lab 2
BIO 101
Evolution via natural selection
What would happen if all of the trees
and dinosaurs were the same size?
Individual variation is necessary for
natural selection to occur.
What would happen if all the dinosaurs
produced just one offspring?
Differential fitness is necessary for
natural selection to occur.
What would happen if offspring never
resembled their parents?
Parents:
Offspring:
✖
Traits must be heritable for natural
selection to occur
Parents:
Offspring:
✖
Conditions required for natural
selection to occur:
Individual variation: members of a species differ
in their characteristics
Mode of inheritance: parents pass on some of
their traits to their offspring
Differential fitness: some individuals leave more
offspring than others due to their special inherited
traits
Classification System
We’ll be
looking at all
of these!
Ancestral
Eukaryote
Protists are
everywhere in
Eukarya!
“the junk
drawer of the
eukaryotes”
We’ll be
looking at all
of these!
Ancestral
Eukaryote
Protists are
everywhere in
Eukarya!
“the junk
drawer of the
eukaryotes”
6 Kingdoms
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Plants (Plantae)
Animals (Animalia)
Fungi (Fungi)
Eubacteria
Archaeabacteria
Protista
A constantly changing system…
Linnaeus[5] Haeckel[6]
(1735)
(1866)
2 kingdoms 3 kingdoms
Animalia
Vegetabilia
Chatton[7]
(1925)
2 groups
Animalia
Plantae
Eukaryote
Copeland[8] Whittaker[2] Woese [9][10]
(1938)
(1969)
(1977,1990)
4 kingdoms 5 kingdoms 3 domains
Animalia
Animalia
Plantae
Plantae
Protoctista
(not
treated)
Protista
Prokaryote
Monera
Fungi
Eukarya
Protista
Monera
Archaea
Bacteria
Euglena
- Heterotrophic and phototrophic (can engulf food via phagocytosis, or use sunlight)
- Flagellated
Paramecia
- Heterotrophic only
- Ciliated
- Harbors endosymbiotic green algae that provide food in exchange for protection
Dinoflaggelates
Diatom diversity
Diatom cell wall made of silica
Animals!
– Hydra (Cnidaria)
• Baby jellyfish that never
become adults.
• Radial symmetry
– Rotifers (Rotifera)
• Wheel animals
• Bilateral symmetry
A note on symmetry
• Bilateral symmetry last to
evolve, approx. 555 mya.
• Radial symmetry is older, and
contains only corals, sponges
and jellies.
Phylum Cnidaria – Hydras (Hydra)
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Two tissue types, no organs – no anus!
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Includes: corals, jellies, sea anemones, and
Portuguese men-of-war. (9000+ spp!)
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Most species are marine, few freshwater spp.
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Generally two body forms present in the life cycle:
– Umbrella-like, free-swimming stage (called a
medusa)
– Cylindrical, attached or stationary form –
often grows into colonies of individuals
(called a polyp)
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Hydra exist only as polyps
Random cool stuff about Hydras
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They are capable of morphallaxis
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Nematocysts
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Regeneration into entirely new individuals
Because of this, they might be biologically
immortal.
Cnidocytes are the stinging cells
Explosively discharge harpoon
Contain neurotoxins which immobilize prey
Two body layers
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Epidermis on the outside
Gastrodermis on the inside
Adult medusa
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They’re hermaphrodites
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Some have symbiotic relationships with
algae
Phylum Rotifera - Rotifers
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Very small animals – most 0.1 – 0.5 mm in
length
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Most common in freshwater, though some
salt water species
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Important part of freshwater zooplankton,
being a major food source and many species
contributing to decomposition of organic
matter.
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Pharynx contains tiny, calcified, jaw-like
structure called trophi
Other neat things about rotifers
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They have “cement glands” which excrete an
adhesive to hold them down.
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They have an anus!
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They can reproduce sexually or
parthenogenetically – development of an
embryo without being fertilized (like some
reptiles and fish) (also, they’re dioecious – only males
They have a brain! (hydra have nerve webs)
and females, no hermaphrodites)
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Resting eggs – eggs which develop into
zygotes that can survive very harsh conditions
(like winter)
Think about…
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Morphological characteristics
Ecology of the organism
How does the organism get around?
What role do they play in the ecosystem?
Do they have any economic value?
Where do they live?
• Don’t know the answer?? It’s probably a great
research question! Ask me about it.