Download Hewitt/Lyons/Suchocki/Yeh, Conceptual Integrated Science

Classifying Living Things
Thousands of years ago, Aristotle arranged
a “chain of being.” Other scientists used
this strategy to arrange living things from
“simple” to “complex.” Humans were at the
top of the chain.
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King Phillip Comes Over For Good
Spaghetti
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Kingdom
Phylum
Class
Order
Family
Genus
Species
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Classifying Living Things
In the 18th century, Linnaeus developed a system for
classification that emphasized the shared similarities of
organisms.
This system classified organisms using a number of
hierarchical levels, from domain to species.
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Diversity on Earth
• Diversity: variety of
living organisms
• Estimated between 515 million species
• Only 1.5 million have
been described
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Common vs. Scientific Names
• Scientific names eliminate confusion
• Binomial nomenclature is the universal
language for the organization of species.
• Different areas use different common
names for the same species.
• The same common name is also used for
different species.
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Common Names for
Lutjanus griseus
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gray silk
mangrove snapper
mangrove pargue
mango snapper
pargue
black pargue
black snapper
lawyer
silk
snapper
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Linnaeus’s Classification
System
• Swedish botanist (1707-1778)
• Binomial Nomenclature – two-part
scientific name  Genus species
• Why Latin?
• Latin was the language known universally by the
educated
• Also used as a descriptor
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Classifying Living Things
Biologists now classify life based on its
evolutionary history. This system:
• Is more exact
• Allows scientists to make predictions
• Helps biologists study the evolution of
specific features
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Classifying Living Things
The evolutionary history of living things can
be diagrammed in a cladogram.
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Classifying Living Things
Some well-known Linnaean groups are also clades.
However, other Linnaean groups are not clades.
For example, the cladistic system places birds among the
reptiles, while the Linnaean system does not.
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Classifying Living Things
CHECK YOUR NEIGHBOR
Why would Linnaeus separate birds from
reptiles? Why would the cladistic system
put them in the same clade?
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Classifying Living Things
CHECK YOUR ANSWER
The Linnaean system grouped organisms using
shared characteristics. It seemed natural to
separate feathered, flying, “warm-blooded” birds
from scaly, terrestrial, “cold-blooded” reptiles.
But the cladistic system groups organisms
according to shared ancestry, which puts birds in
the reptile clade.
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The Three Domains of Life
Life is classified into three domains:
• Bacteria
• Archaea
• Eukarya
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Domains
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The Three Domains of Life
Domain Eukarya is divided into four
kingdoms:
• Plants
• Fungi
• Animals
• Protists (everything that doesn’t fit into the
other three kingdoms)
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Bacteria
Bacteria are diverse:
• Some bacteria are autotrophs that
photosynthesize. Others are heterotrophs.
• Most bacteria are single celled, but others
gather in clusters.
• Bacteria reproduce asexually by dividing, but
most occasionally exchange some genetic
material.
• Bacteria vary in shape, and some have flagella
for locomotion.
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Bacteria
Important functions of bacteria from a human’s
point of view:
• They break down organic matter, releasing
carbon for photosynthesis.
• They help make nitrogen available to living
things.
• Some produce vitamins in the bodies of humans.
• Some prevent harmful bacteria from infecting
our bodies.
• Some are essential for making cheese, yogurt,
and some drugs.
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Archaea
Archaea are not bacteria. They are a distinct
domain of prokaryotic organisms.
Some archaea are “extremophiles” that
thrive in harsh, salty, or very hot
environments. Others are
chemoautotrophs that make food using
chemical energy from molecules such as
hydrogen sulfide.
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Protists
Protists are eukaryotes that are not plants,
fungi, or animals.
They may be single celled or multicellular,
reproduce through asexual or sexual
means, be autotrophs or heterotrophs.
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Protists
Protists are diverse. They include:
• Many seaweeds
• Diatoms
• Amoebas
• Disease-causing organisms such as
Plasmodium, which causes malaria
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Plants
Plants are autotrophic, multicellular,
terrestrial eukaryotes that obtain energy
through photosynthesis.
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Plants
Plant adaptations to the terrestrial world
include:
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Roots
Shoots
Leaves
Vascular system
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Plants
Plant reproduction occurs through
alternation of generations.
The plant life cycle alternates between a
haploid stage (gametophyte) and a diploid
stage (sporophyte). The details vary by
type of plant.
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Plants—Mosses
Mosses are small, seedless plants with no
vascular system. Every part of the moss
has to absorb water directly via diffusion.
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Plants—Ferns
Ferns are seedless plants with feathery
leaves. Most live in moist, shady habitats.
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Plants—Seed Plants
Seed plants have two key features that make them
successful in many habitats:
• Pollen—immature male gametophytes that can be
transported to female gametophytes by wind or animals
• Seeds—embryonic plants that are encased in a tough
outer coating with a food supply. Flowering plants
surround their seeds with a fruit.
The two major types of seed plants are flowering plants
and conifers.
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Plants—Seed Plants
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Fungi
Fungi are more closely related to animals
than to plants. They are heterotrophs.
Fungi may be single celled or multicellular
and may reproduce sexually or asexually.
Many fungi are decomposers—they play a
crucial role in terrestrial ecosystems.
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Animals
Animals:
• Multicellular, heterotrophic eukaryotes that
obtain nutrients by eating other organisms.
• Most reproduce sexually and are diploid
during most of their life cycle.
• The gametes—sperm and egg—are the
haploid stage of the life cycle.
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Animals
This drawing shows the evolutionary
relationships among the various animal
groups.
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Animals—Sponges
Sponges are sedentary marine animals.
Special cells in the sponge beat flagella that move
water through the sponge, allowing cells to
capture food, digest it, and then distribute
nutrients to other cells.
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Animals—Cnidarians
Cnidarians:
• Include jellies, sea anemones, corals, and hydras
• Have two distinct tissue layers separated by a jelly-like middle
layer
• Use tentacles to catch prey
• Alternate between a sedentary polyp stage and a bell-shaped
medusa stage, although some groups exist primarily in one
form (corals are polyps, jellyfish are medusae)
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Animals—Flatworms
• Flatworms feature distinct head and tail
ends and back and belly sides.
• A single opening serves as mouth and
anus.
• The flat shape allows the animal to obtain
oxygen across the skin via diffusion.
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Animals—Roundworms
Roundworms:
• Small, slender bodies
• Both a mouth and an anus
• Tough outer cuticle
• Longitudinal muscles
• Move like flailing whips
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Animals—Arthropods
Arthropods include crustaceans, chelicerates
(ticks, spiders), and uniramians (centipedes,
millipedes, and insects).
All feature:
• An exoskeleton
• Segmented bodies and
jointed legs
• A brain
• Developed sense organs
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Animals—Mollusks
Mollusks:
• Soft-bodied animals
• Most have a protective shell
• Use a muscular foot for locomotion
• Visceral mass holds the digestive and
reproductive organs
• Mantle secretes the shell
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Animals—Mollusks
Mollusks include:
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Bivalves (clams, scallops)
Cephalopods (squids, octopuses)
Gastropods (snails, abalones)
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Animals—Annelids
Annelids are segmented worms, such as
earthworms and leeches.
The muscles of earthworms are oriented
both circularly and longitudinally, providing
flexibility in motion.
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Animals—Echinoderms
Echinoderms (sea stars, sea cucumbers)
have endoskeletons and tube feet.
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Animals—Chordates
Chordates include tunicates, lancelets, and
vertebrates.
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Animals—Chordates
All chordates have, at some point in their life
history,
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A brain and spinal cord
A notochord that supports the back
Gill slits
A tail
Some of these features are not apparent in
adults. Human embryos do go through a tailed
stage.
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Animals—Chordates
Vertebrates include:
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Many groups of fishes
Amphibians
Reptiles
Mammals
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Animals—Chordates
Amphibians:
• Include salamanders, frogs, and caecilians
• May have aquatic larvae and terrestrial adults
• Must live in moist environments to protect their skin and
eggs
• Are vulnerable to pollution and environmental
contamination
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Animals—Chordates
Reptiles and mammals are amniotes:
• Skin made of dead cells
• Shelled eggs
• Well adapted to diverse terrestrial habitats
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Animals—Chordates
Reptiles include birds. All reptiles other than
birds are ectotherms. Ectotherms
regulate their body temperature
behaviorally.
Birds and mammals are endotherms. They
maintain a constant body temperature by
metabolizing large amounts of food.
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Animals—Chordates
Mammals:
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Have hair
Feed milk to their young
Are endotherms
May be terrestrial, aquatic, or able to fly
Include monotremes (egg layers like the
platypus), marsupials (kangaroos), and
placentals (humans).
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