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Chapter
26Animals
26 – 1 Introduction to the Animal Kingdom
• Of all the kingdoms of organisms, the animal kingdom is the most diverse in appearance
What Is an Animal?• Animals are Multicelular
• Animals are Eukaryotic heterotrophs
• Animal cells lack cell walls
• Animals belong to the kingdom Animalia
• The bodies of most animals contain tissues
• Ex.)epithelial, connective tissue (bone, blood) nervous tissue
• Animals are informally grouped into 2 categories
Invertebrates
• Animals that don’t have a backbone
• Over 95% percent of all animal species are grouped into this category
Vertebrates • Animals that have a backbone
What Animals Do To Survive
• Animals carry out the following essential functions:
1. Feeding/Digesting
Intracellular digestion • Process in which food is digested
inside cells
Extracellular digestion• Process in which food is broken
down outside the cells in a digestive tract
2. Respiration (gas exchange)
Ex.) skin, gills, lungs
3. Circulation
Open circulation • System in which blood is not
always continued within a network of blood vessels
Closed circulation • System in which
blood is contained within a network of blood vessels
4. Excretion
5. Response
6. Movement/Support
Hydrostatic skeletons • Layers of
circular and longitudinal muscles that enable movement
Ex.) worms
Exoskeleton• External skeleton; tough external
covering that protects and supports the body of many invertebrates
Ex.) insects
Endoskeleton• Structural support located inside
the body
Ex.) sea stars, humans
7. Reproduction• Can be sexual or asexual
Hermaphrodites • Individuals that have both male
and female reproductive organs
External fertilization • Eggs are fertilized outside the
female
Internal fertilization• Eggs are fertilized inside the
female
Oviparous• Eggs hatch outside the mother
Ovoviviparous• Eggs hatch inside the mother
Viviparous• Babies are born live and get
nourishment from the mother
Trends in Animal Evolution
• Complex animals tend to have high levels of cell specialization and internal body organization, bilateral body symmetry, a front end or head with sense organs and a body cavity
Cell Specialization and Levels of Organization
• As animals evolved, their cells have become specialized to carry out different functions
• Ex.) Movement, digestion, nervous system
• Large animals need greater efficiency in body processes than smaller animals
• Groups of specialized cells form tissues, which join together to form organs and organ system - all of which work together to carry out a variety of complex functions
Body SymmetryAsymmetry – no symetry
Ex.) sponges
Radial symmetry• Body plan in which body parts
repeat around the center of the body
Ex.) jelly fish, sea star
Bilateral symmetry• Body plan in which only a single
imaginary line can divide the body into 2 equal halves
Ex.) worms, insects, chordates
Cephalization• Most animals with bilateral
symmetry also have a trend toward cephalization
Cephalization
• Concentration of sense organs and nerve cells at the front of an animals body
• Organisms with cephalization can respond to the environment in more sophisticated ways than can simpler organisms
Body Cavity Formation• Most animals have a body cavity which is
a fluid filled space that lies between the digestive tract and the body wall
• A body cavity is important because it provides a space in which internal organs can be suspended so that they are not pressed on by muscle or twisted out of shape by body movements
• Body cavities also allow for specialized regions to develop, and they provide room for internal organs to grow and expand
Adaptive Radiation• Over the course of evolution, the
appearance of new adaptations – such as jaws and paired appendages – has launched adaptive radiations in chordate groups
Adaptive radiation • Rapid growth in
the diversity of a group of organisms
Convergent Evolution• Adaptive radiations sometimes
produce species that are similar in appearance and behavior, even though they are not closely related. This trend is called convergent evolution
Kingdom Animalia
Major Phyla
Phylum Porifera (Sponges)
Asymetrical
Some specialized cells
Phylum Cnidaria
Radial Symmetry
Stinging Cells
Tentacles
Nerve Net
Two Body Forms
Cnidarian Lifecycle
Asexual Reproduction
Coral
Sea Anemones
Box Jellyfish
Portuguese Man-of-War
Phylum Platyhelminthes
Flatworms
Flattened Body, one opening
Bilateral Symmetry
Sexual or Asexual Reproduction
Budding
Some are parasites
Tape worm mouth parts
Phylum Nematoda
Roundworms
Round Body, tapered at both ends, two openings
Bilateral symmetry
Heartworm
Ascaris
Trichinella
Elephantitus
Phylum Mollusca
Mollusks
One Shell
Two Shell
No Shells
Nautilus
Squid
Octopus
Bilateral Symmetry
Phylum Annelidia
Segmented Worms
Leech
Clamworm
Feather dusters
Phylum Arthropoda
Arthropods
Arthropod Traits• Segmented body, jointed legs,
exoskeleton• Bilateral symmetry• Tissues and organs
– Open circulatory system– Complete digestive tract– Simple excretory organs– Brain and nerve cords
• Sexual reproduction (separate sexes)
5 Major Arthropod Classes
Centipedes
Millipedes
Crustaceans
Crustaceans
Crustaceans
Crustaceans
Crustaceans
Insects
Insects
Insects
Arachnids
Arachnids
Arachnids
Arachnids
Phylum Echinodermata
Echinoderms
Echinodermata = Spiny Skin
Water Vascular System
Tube Feet
Radial Symmetry
Brittle Sea Star
Sea Star
Sand Dollar
Sea Urchin
Sea Cucumber
Sea Star Eating
Phylum Chordata
Chordates
Chordate Traits• Dorsal notochord at some time• Pharyngeal gill slits (or pouches)
at some time• Dorsal hollow nerve cord at some
time• Bilateral symmetry
Chordate Traits• Tissues and organs of vertebrates
– Backbone– Brain and nervous system– Closed circulatory system– Complete digestive tract– Paired kidneys– Gills or lungs– Paired image forming eyes
• Sexual reproduction (separate sexes)
Invertebrate Chordates
2 groups
Tunicates
Lancets
Vertebrate Chordates
7 classes
1. Agnatha
Lamprey
2. Chondrichthyes
2. Chondrichthyes
2. Chondrichthyes
3. Osteicthyes
3. Osteicthyes
3. Osteicthyes
Swim Bladder
4. Amphibia
4. Amphibia
4. Amphibia
Two Stage Life Cycle
5. Reptilia
5. Reptilia
5. Reptilia
6. Aves
6. Aves
6. Aves
6. Aves
7. Mammalia
7. Mammalia
7. Mammalia
7. Mammalia
7. Mammalia