Animal Taxonomy

By the end of this class you should understand:

• The system of taxonomy and the major levels of taxonomy

• The major phyla of animals and their distinctive features

• How to watch an hour of funny videos and still learn something for biology class

Taxonomy

• Phylogeny is the study of the “tree of life”– What organisms are descended from what

common ancestors

• Taxonomy is the practice of labeling groups by their common ancestry– Somewhat arbitrary– Originates from Aristotlean thinking

The Current Tree of Life

Levels of Taxonomy

• Originally there were two “Kingdoms” of life– Animals and Plants

• Then there were three– Animals, Plants, and Protists

• When I was in high school there were five– Animals, Plants, Fungi, Protists, and “Monera”

(bacteria)

• Now there are a lot

Animal Kingdom

• All animals are still referred to as being in one Kingdom, Animalia

• All animals are multicellular organisms that must eat other things and have no cell walls– No photosynthesizers here!

• The diversity of animal life is staggering

Levels within Kingdom

• Within any kingdom there are multiple smaller groups of organisms with a common ancestor, known as a phylum– Each phylum has many key characteristics in

common• Each phylum has many classes of organisms– Classes contain orders, which contain families,

which contain genuses, which contain species– KPCOFGS

Animal Phyla

• All animals with a backbone (vertebrates) belong to just one phylum, chordata– All other animals belong to many different phyla

which are all invertebrates

• The more closely related another phylum is to chordates, the more traits they have in common

Animal Phylogeny

Selected Phyla of Animals

• Porifera (sponges)• Cnidaria (jellyfish & corals)• Annelida (earthworms)• Mollusca (snails & octopi)• Arthropoda (insects & crustaceans)• Echinodermata (starfish)• Chordata (vertebrates)

Porifera

• Sponges are the simplest animal life– Not mobile– Cells not organized into tissues

• Feed by filtering water through their body

Cnidaria

• Body is organized into tissues• Have stinging tentacles that

inject venom into anything they touch– Hunt prey by stinging and then

dragging into gut• Have a very simple nervous

system• Do not have bilateral

symmetry

Annelida

• Worms such as annelids are more “advanced” than cnidarians because they have bilateral symmetry

• Annelids have organs and a more advanced circulatory system– Earthworms and other

marine worms are in this group

Mollusca

• Mollusca is a very diverse phylum

• Mollusca has very simple organisms (snails in class gastropoda) and more advanced animals (octopi in class cephalopoda)– Similar to fish and mammals

both belonging to phylum chordata

Mollusca Diversity

• https://www.youtube.com/watch?v=VTV23B5gBsQ

• https://www.youtube.com/watch?v=st8-EY71K84

• https://www.youtube.com/watch?v=GDwOi7HpHtQ

Arthropoda

• Arthropods are animals that have an exoskeleton and jointed legs

• The largest phylum of animals in terms of both species diversity and number of living animals

Arthropoda Diversity

• https://www.youtube.com/watch?v=F5FEj9U-CJM

• https://www.youtube.com/watch?v=0aSCPmabRpM

• https://www.youtube.com/watch?v=Q1zbgd6xpGQ

Echinodermata• Echinodermata appears at first

glance to be related to corals or sponges but actually are closely related to chordates– The hint is that their embryos start

out with bilateral symmetry and the initial opening becomes their anus, just like chordates

• Have a bony endoskeleton and a water pump system to help them crawl along the ocean floor

Echinodermata Diversity

• https://www.youtube.com/watch?v=_y4DbZivHCY

Chordata

• Chordata started out in the ocean, and the first chordates probably resembled the modern lancelet (a very simple fish with no brain)

• Fish are a modern class of chordates that evolved from a common ancestor that was much like a lancelet– Fish are much more advanced swimmers

by now– Natural selection! Slow swimmers are

dinner!

Fish Diversity

• https://www.youtube.com/watch?v=UqYUTTqupOY

• https://www.youtube.com/watch?v=Z-BbpaNXbxg

Amphibians

• Amphibians evolved from fish and became the first land animals– The common ancestor of fish and

amphibians probably didn’t have scales yet

• They still rely on water to breathe through their skin and to reproduce

Amphibian Diversity

• https://www.youtube.com/watch?v=ndQZBQJf034

Reptiles

• Reptiles are a class of animals that evolved from a common ancestor with amphibians

• Have scaly skin to avoid losing water and their eggs have a membrane called an amnion to prevent losing water

Reptile Diversity

• https://www.youtube.com/watch?v=UR_byRbXxvs

Birds

• Birds have a common ancestor with modern reptiles since they are evolved from dinosaurs

• Birds all have feathers, though not all can fly, and scaly legs much like a reptile’s

Bird Diversity

• https://www.youtube.com/watch?v=6k01DIVDJlY

• https://www.youtube.com/watch?v=XeFxdkaFzRA

Groups of Mammals

• Mammals are a class of phylum chordata that has a lot of diversity– All mammals have some kind of hair and produce milk

for their young• The three subclasses of mammals are

monotremes, marsupials, and placental mammals– Monotremes lay eggs– Marsupials have a pouch that their baby lives in– Placental mammals give birth to fully formed babies

Monotreme Diversity

• https://www.youtube.com/watch?v=L6kAE06mJAQ

Placental Mammals

• There are many orders of mammals within class mammalia– Rodents– Carnivores– Hoofed animals

(actually two orders)– Elephants

Mammal Diversity

• https://www.youtube.com/watch?v=110iUX1Ursk

• https://www.youtube.com/watch?v=XrUM8m2rnP0

• https://www.youtube.com/watch?v=eHi9FvUPSdQ

• https://www.youtube.com/watch?v=fio1NUxszhY

Order Primata• Primates are an order

of mammals that have a number of traits in common– Ball-and-socket

shoulder– Opposable thumb– Forward-facing eyes for

good distance judgment

• Evolved to live in trees, most primates still do

Primate Diversity

• https://www.youtube.com/watch?v=jHs5POy8-8Y

• https://www.youtube.com/watch?v=6Jz0JcQYtqo

See you in lab!

• Tomorrow: more on the physiology and evolution of these groups!