animal diversity

why do phylogeny’s matter

evolutionary context, speciation and extinction, and geographic history

homology

character similarity resulting from common ancestry

homoplasty

character similarity NOT resulting from common ancestry

Synapomorphy

derived character shared by members of a clade

Plesiomorphic

character states are ancestral for a taxon.

Symplesiomorphy

is the sharing of ancestral characters.

Monophyly

Includes the most recent common ancestor AND all of its descendants.

Paraphyly

Includes the ancestor and SOME, but not all, of its descendants

Polyphyly

Does NOT include the most recent common ancestor of all group members.

Phylogenetic Systematics / Cladistics were formulated by

Willi Henning

classification

Fish” — grouped by shared traits

systematization

grouped by common ancestry

A whale's flipper, a bird's wing, and a human arm share the same underlying bone arrangement inherited from a common ancestor. An octopus's camera-type eye and a vertebrate's camera-type eye look remarkably similar but evolved independently. These two patterns illustrate the difference between:

 

Homology and homoplasy

For decades, researchers have debated whether sponges or ctenophores (comb jellies) are the sister lineage to all other animals. Different genomic datasets—and even different types of data, like gene sequences versus gene order—have supported different answers. What does this debate best illustrate about systematics?

 Resolving deep evolutionary splits often requires weighing multiple lines of evidence, and disagreement can persist even as new data accumulate.

what are the major axes of variation in an animal body plan

grade organization, body symmetry, number of germ layers, body cavity

what is the order of grade organization

protoplasmic, cellular, cell-tissue, tissue-organ, organ-system

protoplasmic:

unicellular organisms

cellular:

functionally differentiated cells

cell tissue:

aggregates of cells that form tissues

tissue organ:

aggregates of tissues that form organs

organ system:

aggregates of organs to form organ systems

spherical symmetry:

any plane passing through the center divides the body into equal halves. (great for rolling/floating, mostly in protists)

radial symmetry

can be divided into similar halves by more than two planes passing through the longitudinal axis. (usually sessile, free floating, or weakly swimming) (can interact with the environment in all directions) ex: jellyfish, sea anemones, corals

bilateral symmetry:

can be divided along a sagital plane in two mirrored portions (bilateria)

cephalization

differentiation of a head, moving head first

what is a body cavity

an internal space

what surrounds body cavities

germ layers

what is the only animal with no germ layers or gut

sponges

what are the two types of body cavity developments

diploblastic and triploblastic

diploblastic:

endoterm and ectoderm

how many cavities do diploblastics have

two cavities- blastocoel and gastrocoel

triploblastic:

endoderm, mesoderm, ectoderm (one of two activies)

what are the three mesoderm body plans

acoelomate, psuedocoelomate, coelomate

acoelomate:

no body cavity

psuedocoelomate:

body cavity between endoderm and mesoderm

coelomate

body cavity surrounded by mesoderm

what are the two ways that coeloms can arise:

schizocoely and enterocoely

describe schizocoely:

Mesodermal cells fill the blatocoel, forming a solid band of tissue around the gut. Then, a space opens inside the mesodermal band

describe enterocoely:

portions of the gut lining forms pockets that pinch off and form a ring of mesoderm

protosomes are

acoelomate, pseudocoelomate, or coelomate (schizocoely)

deuterostomes are

coelomate (enterocoely)

what are cleavage patterns

describe how cells divide early in development

Blind or incomplete gut:

food enters and exits through the same hole

complete gut

food moves from mouth to anus (tube within a tube)

to be truly multicellular, an organism must:

specialize cell function/ limit reproduction to certain cells

all animals are:

multicellular and belong to metazoa

Choanoflagellatesn are

solitary or colonial protozoans

choanocytes are

specialized sponge cells

epithelium covers

entire internal and external surfaces of your body

T or F: true epithelium is a key characteristic of most, but not all animals

true

what is the phylum, porifera

sponges

what are some characteristics of phylum porifera?

• body has ostia (pores), canals, and chambers

• cellular level of organization - no true tissues or organs

• no germ layers or gut cavity

• radial symmetry or none

• excretion and respiration by diffusion

what are the types of cells in a sponge body

Choanocytes, Pinacocytes, and Archaeocytes

what are choanocytes?