Download INVERTEBRATE ZOOLOGY Three Domains of Life

INVERTEBRATE
ZOOLOGY
Three Domains of Life

Three large groups called domains
Bacteria - prokaryotes
 Archaea - prokaryotes
 Eukarya - eukaryotes

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Prokaryotic – cells lack a nucleus

Eukaryotic – cells possess a nucleus and
membrane bound organelles

Classification is
continually changing

Some scientists don’t
subscribe to the three
domain method of
classification

Domain Bacteria
Some still use the Five
Kingdom method
Domain Archaea
Domain Eukarya

Domain Eukarya
consists of several
kingdoms

Protista - single celled
(several kingdoms)

Plantae - multicellular

Fungi - multicellular

Animalia - multicellular
Protists
Kingdom Plantae
Kingdom Fungi
Kingdom Animalia
Diversity of Life

DNA is the molecule responsible for diversity

Specific regions of DNA (genes) code for specific types of
proteins
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Speciation occurs several ways

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Allopatric
Adaptive radiation
Sympatric
If reproductive barriers arise between populations, speciation will
occur
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Prezygotic barriers
Postzygotic barriers
Invertebrate Zoology

Study of invertebrate animals

Inverts make up at least 99% of all extant (living) animal species
on the planet

Over 1,000,000 described spp. (species) on the planet (mostly
insects)

Estimated 10 to 30 million spp. have yet to be described

We will cover 19 (time permitting) of the approx. 35 animal
phyla
Preview of Phyla

Protozoa – animal-like
protists

Do not belong to kingdom
animalia, and thus are not
considered to be invertebrate
animals

Important evolutionary link
between prokaryotes, and
everyday plants and animals
Volvox
Phylum Porifera

Sponges
Phylum Cnidaria

Jellyfish, Anemones, and Corals
Portuguese Man O’ War
Phylum Ctenophora
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Comb Jellies
Phylum Platyhelminthes

Flatworms
Phylum Nemertea

Ribbon Worms
Phylum Mollusca
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Chitons, Clams, Snails, Slugs, Squids, and Octopi
Banana Slug
Phylum Annelida
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Segmented Worms
Phylum Echiura
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Spoonworms
Phylum Sipuncula
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Peanut Worms
Phylum Tardigrada
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Water Bears
Phylum Arthropoda

Horseshoe Crabs, Arachnids, Crustaceans,
Myriapods, and Insects
Phylum Gastrotricha

Name means “stomach hair”
Phylum Nematoda

Roundworms
Caenorhabditis elegans = good
Ascaris lumbricoides = bad
Phylum Rotifera

Wheel bearers
Phylum Phoronida

A lophophorate
Phylum Brachiopoda

Lamp shells, another lophophorate
Phylum Bryozoa

Bryozoans, the largest phylum in the
superphylum Lophophorata
Phylum Echinodermata

Starfish, Brittle Stars, Urchins, and Sea Cucumbers
Phylum Chordata

Phylum Chordata is
the only phylum
containing vertebrate
animals, however,
there are some
invertebrate chordates
Taxonomy

Linnean system (Kingdom, Phylum, Class, Order, Family,
Genus, Species) is almost abandoned

Genus species (binomial nomenclature) is still used

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Lumbricus terrestris
Lumbricus terrestris

Scientists are more interested in evolutionary relationships (how
are organisms similar / different), as opposed to what “What
class do shrimp belong to?”

Taxonomic names, and proposed evolutionary relationships
change frequently
Cladistics

Method embraced by the authors of your text for constructing
evolutionary relationships in the form of phylogenetic trees, or
cladograms

May be assembled according to morphology and/or molecular
data (nucleic acid or amino acid sequences)
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Can be used to infer a great deal about evolutionary relationships

But it is easy to make mistakes
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Homology – good indication of a relationship
Analogy - misleading
Morphological Vs. Molecular Data
Body Plan Data
rRNA Data
Ground Plan

For each Phylum we cover, you want to understand
that group’s ground plan (basic set of characteristics)

These characteristics are useful for determining
differences / similarities between phyla

Ground plan for Phylum Arthropoda (example):
segmented body, chitinous exoskeleton, periodic molts,
and jointed appendages