Animal Diversity
CHAPTER 32 & 33
What phylum?
What phylum?
What phylum?
Animalia
• Kingdom extends far beyond dogs, birds, and humans
- vast array of diversity covers 1.3 million
animal species
- definition is not straight forward because of
exceptions to every criterion
4 defining characteristics
1. nutritional mode – heterotrophs
2. Eukaryotic, multicellular
3. Specialized cells – nerve and muscle
4. Sexual Reproduction
Characterization by Body Plan
• Grade – group of animal species that share the
same level of organizational complexity
• Body plan – set of morphological and
developmental traits that define a grade
a. Symmetry- radial (from the center)
bilateral – half mirrored
b. Tissues – germ layers – ectoderm,
mesoderm, endoderm
c. Body cavities – coelom – fluid filled space
separates digestive tract from outer body wall
Protostomes & Deuterostomes
Protostome vs. Deuterostome
• Cleavage – (P) Spiral (diagonal), determinate
(early fate)
- (D)Radial (parallel or perpendicular),
indeterminate (capacity to develop into complete
embryo)
• Coelom Formation – (P) coelom forms from
splits in mesoderm
(D) coelom forms from mesodermal
outpockets of digestive tube
• Fate of Blastopore – (P) mouth forms from
blastopore (opening of digestive
tube)
(D) mouth forms from second
opening; anus forms from blastopore
Invertebrates
• Animals without
backbones comprise 95%
of world’s known animal
species
• Occupy almost every
kind of habitat from
hydrothermal vents to
frozen tundra
Phylum Porifera
Sponges
•
•
•
- Sessile organisms usually to rocks or
other surfaces
- Can live in shallow or deep
- many different colors
- usually asymmetrical
- lack true tissues
Collar cells (choanocytes) line inner surface
- contain flagellum
- create wavelike current to circulate
gallons of water each day
- brings in food particles
Amoebocytes
- free moving cells
- produce skeleton of spicules
- digest and transfer nutrients
Contain both male and female organs to
cross fertilize to produce more offspring
Phylum Cnidaria
Cnidarians
- include coral, jellyfish, sea anemones
• Polyp (coral, anemones)
– Cylinder, mouth at top
– Tentacles face up
– Sessile
• Medusa (jellyfish)
– Umbrella-shaped
– Tentacles hang down
– Free-swimming
• Stinging cells (Cnidocytes) contain tentacles that sting and
grasp prey
• Enzyme secreted
• Digestion completed by cells
Platyhelminthes
• Flatworms – include
planarians, tapeworms
and flukes
- free living forms,
most are parasitic
- lack true body cavity
- marine or
freshwater
inhabitants
Rotifera
• Rotifers – smaller than most protists
- multicellular, specialized organ systems
- alimentary canal – digestive tube with
separate mouth and anus
-parthenogenesis- reproduction that
produces females from unfertilized eggs
*can produce males but only live long
enough to produce sperm and produce
zygotes resistant to harsh conditions
Molluscs
• Second largest phylum next to
Arthropods
• Soft body creatures
• Some produce shells; made of CaCO3
Common Features
Visceral mass - contains all internal
structures
Specialized foot – used in digging, grasping,
or creeping
Mantle – covers soft body, enclosing internal
organs, some produce shells
Radula – rasplike scrapers used in feeding
Classes
Bivalvia
Gastropoda
Cephalopoda
Annelids
• Annelida meaning little rings;
segmented worms
• Live in marine, freshwater, and
damp soil
Three classes
Oligochaeta – earthworms
Polychaeta – marine worms
Hirudinea - leeches
Nematodes
• Nonsegmented worms or roundworms
- body encased in a tough coat called a
cuticle- sheds as it grows
- alimentary canal
- inhabit moist soil and decomposing matter
in lakes and oceans
* important role in decomposition and
nutrient cycling
- can be parasitic to plants and animals –
“animals that act like viruses”
Arthropods
• Largest and most successful phylum
- mainly insects
Common features
1. hard exoskeleton
2. segmentation of body parts
3. jointed appendages
- used to walk, feed, copulate, defense, and
sensory reception
Arthropods
Subphylum and examples
a. Cheliceriforms –
horseshoe crabs, spiders,
scorpions, ticks
b. Myriapoda – millipedes,
centipedes
c. Hexapoda – insects
d. Crustacea – crabs,
lobsters, shrimp
Phylum Echinodermata
Common features
• Echino- meaning spiny derm- skin
• Radial symmetry from center of organisms
• Endoskeletons of calcium carbonatespicules or spines
• Water vascular system- complex series of
canals running throughout body with
hydralic pressure causing water to enter and
leave through tubes; aids in movement.
• Regeneration of body parts – sea stars
Phylum Echinoderma
Types of Echinoderms
• Sea stars - Asteroidea
• Sea urchins - Echinodea
• Sea cucumbers Holothuroidea
• Brittle stars - Ophiuroidea
• Feather stars - Crinoidea