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Title: Animals
Description: These notes go over the diversity of animals, and how evolution caused species to deviate from one another. These notes were taken for an introductory college biology course.
Description: These notes go over the diversity of animals, and how evolution caused species to deviate from one another. These notes were taken for an introductory college biology course.
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Animals
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Common characterisitics
o Non-sessile heterotrophs
o Multicellular with some specialized cell types
o Most reproduce sexually
Like plants, animals evolved in water first and then transitioned onto land
o The atmosphere was not originally conducive for cellular respiration
The animal phylogeny is marked by several significant changes that took place
o Sponges are the first branch off of the animal phylogeny
▪ The scientific name is Porifera
▪ Do not contain specialized cells, tissues, or organs, and are just
aggregations of similar cells
▪ Filter feeders
• They create a tube and water is able to flow through
• Eats smaller things that float through the tube
▪ Live in the water and are sessile as adults
o The first change in animal evolution is having specialized cells, allowing for organs
and distribution of labor of biological processes within an organism
o Cnidarians are the next branch off of the animal phylogeny
▪ Aquatic organisms such as jellyfish, sea anemones, and corals
▪ Have tentacles to hunt prey and are often very poisonous
▪ Have radial symmetry, meaning it has more than one plane of symmetry
▪ Corals
• Often live symbiotically with autotrophic protists
• Forms reefs up to hundreds of miles long
• Climate change is causing bleaching by killing coral and the symbionts
o The second change in animal evolution has to do with symmetry
▪ All animals, except cnidarians, have bilateral symmetry
• There is only one plane of symmetry
o The third change in animal evolution involves the order of digestive development
▪ During early development the embryo divides into a ball of cells
▪ A hole forms
• In protostomes that hole becomes the mouth
• Include most of the animal biodiversity, and all are invertebrates
• Worms
• Many different types of worms, and some are microscopic
and they are often parasitic
• Can be hermaphroditic in terms of sexual reproduction
• Still unable to self fertilize
• Can cause schistosomiasis
• Disease caused by infection of blood flukes that
causes liver damage
• Public health crisis in tropical areas around fresh
water
• Arthropods
Animals
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Includes insects, arachnids, and crustaceans
75% of all animal species, and 60% of all species total
Have segmented bodies, jointed appendages, and
exoskeletons made of chitin
• Grow by molting
• As they grow, the shed their old exoskeleton and
grow a new one
• Mollusks
• Octopi, squid, snails, bivalves (clams and oysters), etc
• Live in shells for protection
• Some have a muscular "foot" for movement
• In deuterostomes that hole becomes the anus
• Includes chordates and echinoderms
• Echinoderms include starfish, sea urchins, and sand dollars
• Invertebrates with nervous systems
• Have tube feet: little tubular extensions on their
appendages that help them move
• Chordates
• The notochord is a rod of tissue that extends from head to
tail, and in invertebrates this becomes the backbone
• Dorsal hollow nerve chords form the chordate nervous
system, and in invertebrates this becomes the brain and
spinal chord
Vertebrates are a subgroup of the chordates, and is a major group of organisms
o Have a backbone from the notochord
o First vertebrates were jawless fish around 500 mya
o Fins and jaws evolved, allowing easier movement and feeding
o Vertebrates moved onto land around 400 mya
▪ Involved modification of bodily structures
▪ Bones in the fins of the fish underwent changes to ultimately form limbs
o Limbs have undergone even further modification
o Land vertebrates
▪ Amphibians, reptiles, birds (including dinosaurs), and mammals
Title: Animals
Description: These notes go over the diversity of animals, and how evolution caused species to deviate from one another. These notes were taken for an introductory college biology course.
Description: These notes go over the diversity of animals, and how evolution caused species to deviate from one another. These notes were taken for an introductory college biology course.