Tree of life exam 3

What is closely related to metazoans?

Fungi

Opisthokonts

Fungi and Metazoans

Metazoan Synapomorphies

Blastula , Intracellular Junctions, Collagen

Blastula

hollow ball of cells, emergence of specialized cells

intracellular junctions

connect adjacent cells mechanically at the cell membranes or through cytoskeletal elements within and between cells

Collagen

structural protein found in the skin and connective tissue

Metazoan relatives

Choanoflagellates, Filastrea, Ichthyopsorea

Chanoflagellates

a group of free-living unicellular and colonial flagellate eukaryotes considered to be the closest living relatives of the animals.

Clonal multicellularity

Precursor to complex multicellularity, occurs in Chanoflagellates

Chanoflagellates Reproduction

Asexual and sexual( haploid and diploid )

Chanoflagellates are also thought to be precursors of ____ and _____

Neurons and metabolic system

Cambrian Explosion

530 Mya, where all modern life evolved

Burgess Shale

Preservation of soft body organisms, 1st evidence of metazoans

Halucinogenia

Stephan Jay Gould 1989, thought to be a bizarre organism that walked on spoked legs

Pikaia

Found in Burgess shale, Chordate, 1st reconstructed upside down, structure descendent of digestive system

The tree of life used to be a ___ until ___ because of ___

Polytome, 2008 Genomic Data

A Metazoan trait that fooled us

Segmentation, Arthopods and Annelids are not closely related

Major events early in Metazoan Evolution

Evolution of complex multicellular organisms, Innovations for feeding and digestion, evolution of specialized cells, and major changes to body shape and symmetry

Sponge(Porifera)

1st living branch, aquatic, sessile, Mostly oceanic

Number of porifera

~9,000 species

Earliest sponge full body sponge

60 Mya before cambrian explosion

Porifera: Form and Function

Simple tubes with few cell layers(epidermis, Spiclules; collagen; Pinacocytes, Chanocytes), no circulatory system

Sponge Complexity

Asconoid, sycanoid, leuconoid

Most sponges are (complex or not)

Complex

Example of complex sponge

Carnivorous harp sponge

spiclues

Form the middle layer of sponges, made from silica or calcium carbonate, Protection against predators except sea turtles

sponge reproduction

asexual(budding) and sexual(mobile larval phase)

Sponges are (mono or paraphyletic )

monophyletic

Placozoa

Flat animal, sticky hairy plates, few cells thick, many cilia, no eyes, no gut

Number of Placozoa

<10

Sodium Action Potentials And Placozoa

Used for movement

Placozoa feed through

External phagocytosis via the release of digestive enzymes

Placozoa reproduction

sexual and asexual(budding)

Placozoa Fossils are found in the ____

Ediacaran Period

The Locations of ___ are up to debate in the tree of life

Placozoans, ctenophores, and porifera

Ctenophores

Comb jellies, no circulatory system, fluid filled cavity for gas exchange

Structures in Ctenophores

Colloblast, through gut

Colloblast

a cell that is found on the tentacles of a ctenophore and that secretes a sticky substance

through gut

mouth to anus

Ctenophore fossils were found in

Cambrian

Ctenophores were the first animals to

Puke

Ctenophore reproduction

hermaphrodites

New Ctenophore hypothesis

Ctenophores are sister to all animals , Eumetazoa is broken up

Number of Ctenophora

~ 200

Cnidarians

invertebrates that have stinging cells and take food into a central body cavity

Number of Cnidaria

11,000 species

Cnidarian anatomy

Cnidae, tentacles, blind gut( mouth is also anus), no circulatory or respiratory system

Cnidae

stinging cells

Forms of Cindarians

Polyp(anemone), medusa(jellyfish)

Cnidarians fossil record

Cambrian

Cnidarians diversity

Endocindozoa, Hydrozoa, Scyphozoa (the true jellyfish), Anthozoa (true corals, anemones, sea pens)

Endocindoza(Myxozoa)

Parasitic, no Cnidae, simplified bodies

Cnidaria Groups

Medusozoa, Endocinoza, anthozoa

Medusoza groups

Hydrozoa and Scyhoza

Hydroza

Hydra, some freshwater most oceanic, form colonies( feeding and reproductive polyps), chitin exoskeleton(marine)

Hydroza example

Obelia

Hydroza reproduction

Reproductive polyp > Medusa > zygote >planula larva> hybrid colony

Scyhozoans

Jelly fish , dominant medusa stage(sexual)

Scyhozan reproduction

Adult medusa > zygote> Polyp (scyhistoma) > strobila > Young medusa(ephyra)

Number of scyhoza

200 species

Anthozoa

sea anemones and corals, no medusa stage

Bilaterians

Bilateral symmetry, 3 green layers, coelom

Number of Bilaterians

1,462,000 species

Bilateral symmetry

Body plan in which only a single, imaginary line can divide the body into two equal halves.

Bilateral symmetry led to

Cephalization

3 germ layers

ectoderm, mesoderm, endoderm

Ectoderm

the outer germ layer that develops into skin and nervous tissue

Endoderm

the inner germ layer that develops into the lining of the digestive and respiratory systems

Mesoderm

middle germ layer; develops into muscles, and much of the circulatory, reproductive, and excretory systems

Gastrulation

the process in which a gastrula develops from a blastula by the inward migration of cells

Coelom

fluid-filled body cavity lined with mesoderm

Acoelomate

an animal that lacks a coelom, or body cavity

Acoelomate examples

Platyhelminthes

pseudocoelomate

An animal whose body cavity is not completely lined by mesoderm

Pseudocoelomate example

Nematoda

2 Major clades of Bilaterians

protostomes and deuterostomes

Protosomes

blastopore becomes mouth, spiral cleavage, Schizocoeious

Protosome examples

molluscs, annelids, arthropods

Deuterostomes

Radial clevage, blastpore becomes anus, Enterocoeious

2 Major clades in Protosoma

Lophotrochoza and Ecdysozoa

Lophotrochozoa example

Bryozoa, Brachiopodia, Mollusca

Ecdysoza example

Nematoda, arthropods

Platyhelminthes

Flatworms, parasitic or free living, marine, freshwater, terrestrial

Platyhelminthesis stucture

Muscles, nerves, flame bulb, mouth, eyes, guts(in some)

Flame bulb

specialized hollow excretory or osmoregulatory structure

number of platyhelminthes

20,000

Why are Platyhelminthes important?

They kill hundreds of thousands of people

Platyhelminthes fossil record

1st evidence, hooks in Devonian fish

Grouping of Platyhelminthesis

Tubellaria and trematoda and cestoda

Tubellaria

Free-living flatworms; not parasites; Most in marine or fresh water, lots of cillia

Trematoda

flukes, parasitic, Schistomiasis, complex life cycle

Trematoda life cycle

Eggs > larvae > snail> burrow into human skin

Schistosomiasis

infection with a blood fluke that is carried by a snail; it poses a common problem in tropical countries

Cestoda

Tapeworm, no mouth, no gut

Cestoda spread

Human poop infested by pigs, fleas with eggs in them eaten by dogs

Tapeworms can lead to death or seizures by

Creating cysts in a person's brain

Platyhelminthes reproduction

sexual(hermaphodites, cross fertilizing, penis jousting and asexual(regenerative capabilities)

Rotifers

Wheel animals, psedocelomate, colonial,

Rotifer structure

No circulatory system; head, body and trunk; Mastax

Mastax

the muscular pharynx in rotifers