TRENDS IN ANIMAL EVOLUTION
CELL SPECIALIZATION
CEPHALIZATION
EARLY DEVELOPMENT
BODY SYMMETRY
BODY CAVITY FORMATION
CELL SPECIALIZATION
CELLS FORM TISSUES, TISSUES FORM ORGANS, ORGANS FORM ORGAN SYSTEMS
– EPITHELIAL (skin, lining of cavities)
– CONNECTIVE (bone, blood)
– MUSCULAR (heart, biceps)
– NERVOUS (brain, nerves)
EARLY DEVELOPMENT
FERTILIZATION FORMS A ZYGOTE
BLASTULA (hollow ball of cells)
GASTRULA (germ layers form)
GERM LAYERS
The gastrula is made up of three parts:
– Ectoderm, a layer of cells on the outer surface of the gastrula, grows and divides developing into skin and nervous tissue.
– Endoderm, a layer of cells lining the inner surface of the gastrula, develops into the lining of the animal’s digestive tract.
– Mesoderm, made up of two layers of cells lying between the ectoderm and endoderm, forms muscles, reproductive organs and circulatory vessels.
2 TYPES OF DEVELOPMENT
PROTOSTOMES
– mouth forms from the opening (blastopore) of the gastrula
– Mollusca, Annelids, Arthropods
DEUTEROSTOMES
– anus forms from the opening (blastopore) of the gastrula during development
– Echinodermata and Chordata
3 TYPES OF BODY SYMMETRY Asymmetrical-no symmetry (ex,
sponge) Bilateral- body plan in which single line can divide body into 2 equal parts
Radial-body plan in which body parts repeat around center of body
ANATOMICAL TERMS
Dorsal- top or back
Ventral- bottom
Anterior- head end that goes first
Posterior- tail end that follows
Lateral- along the side (lengthwise)
BODY PLANS OR BODY CAVITY FORMATION
ACOELOMATE- no body cavity b/w digestive tract and outer body wall
ex. Platyhelminthes (flatworms)
BODY PLANS OR BODY CAVITY FORMATION
PSEUDOCOELOMATE- slight body cavity between the mesoderm and endoderm
Ex. Nematoda (roundworms)
BODY PLANS OR BODY CAVITY FORMATION
COELOMATE- body cavity forms and cushions organs, allows for growth of organs.
Ex. Annelids (earthworm)
FEEDING HETEROTROPHS
OMNIVORES- feed on both vegetation & other animals
FILTER FEEDERS- feed by
straining tiny floating plants
FEEDING HETEROTROPHS
DETRITUS FEEDERS- feed on tiny
bits of decaying matter
PARASITES- feed on living organisms
usually destroying or injuring the host organism
PROTECTION AND SUPPORT
Though not all animals have a skeleton, those that do can be divided into two groups:
– Those with an EXOSKELETON – a hard, waxy coating on the outside of the body that protects internal organs, provides a framework for support, and a place for muscle attachment.
– Those with an ENDOSKELETON – support framework within the body that protects some organs and a brace for muscles to pull against.
PHYLA IN KINGDOM ANIMALIA
There are around 2 million species and 35 phyla in kingdom Animalia, the majority of organism are represented in just 9 of those phyla.
• Porifera
• Cnidaria
• Platyhelminthes
• Nematoda
• Annelida
• Arthropoda
• Mollusca
• Echinodermata
• Chordata
2 MAIN GROUPINGS OF ANIMALS
INVERTEBRATES
– 95% of animal species
– No backbone
VERTEBRATES
– 5% of animal species
– Contains backbone
Invertebrates
Porifera- The Sponges
– Marine
– Asymmetical
– Filter feeder
Cnidaria- The Cnidarians
– Marine
– Stinging tentacles
– Radial symmetry
Invertebrates
Platyhelminthes- The Flatworms
– Marine or terrestrial (parasite)
– Bilateral symmetry
– Acoelomates
Nematoda- The Roundworms
– Marine or terrestrial (parasite)
– Bilateral symmetry
– Has mouth and anus
Invertebrates
Annelida- The Segmented Worms
– Marine or terrestrial
Arthropoda- The Arthropods
– Exoskeleton and jointed appendages
Invertebrates
Mollusca- The Mollusks
– Terrestrial or marine
– Bilateral symmetry
Echinodermata- The Echinoderms
– Marine
– Radial symmetry
– “spiney skinned”
Subphylum Vertebrata
Chondrichthyes and Osteichtyes
– The fish: cartilaginous and bony
– a vertebrate that lives in water, swims, has gills and fins and is usually covered with scales
– simplest and largest group of vertebrates
Vertebrata
Amphibia – a cold-blooded vertebrate
that generally spends some time in water and some time on land
– Smooth, moist skin
– Live in moist, cool places
– Lose gills and grow lungs as they grow up
– Most lay eggs in water
– Examples: Frogs, toads, salamander, and mud puppy
Reptilia – a cold-blooded vertebrate that is
covered with scales or horny plates
– Dry, rough skin
– Most lay eggs on land
– Live in warm, dry places
– Have lungs all their lives
– Examples: lizards, snakes
Vertebrata
Aves
– a warm-blooded vertebrate with a beak, wings, and feathers
– Additional Adaptations MOST Birds Have: ability to fly, instinct to migrate
– Penguins are birds even though they cannot fly
Mammalia
– a warm-blooded vertebrate with hair or fur that nurses its young and has babies that are born live