Kaarten: L25: Animal phylogeny | Quizlet

Kindom multicellular

Plants, fungi, animals

Endosymbiosis

A theorized process in which early eukaryotic cells were formed from simpler prokaryotes.

The universal common core of the ribosome

Translate mRNA into proteins. Its assumed that their is a common ancestor that had ribosomes. Ribosomes are well preserved, so we can indicate well how/what the ancestor was.

Why are there few multicellular species?

Because size matters! To have a large size, a great level of organization is needed.

Grades of Organization

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

Protoplasmic

unicellular organisms, protoplasm divided into organelles

Cellular Organization

All living things are composed of one or more cells

Cell tissue organization

tissue; specialized cells are grouped together to perform as a unit; jellyfish

Tissue-organ grade

aggregation of tissues into organs

Tissue-system grade

Organs working toghether to perform some kind of function. Examples are circulation, digestion and respiration.

When getting more complex, what should be increased?

Order

phylogenetic constraint

trait that arose in the past that has no positive selective advantage under present conditions.

Choanoflagellates

a group of free-living unicellular and colonial flagellate eukaryotes considered to be the closest living relatives of the animals.
- Protoplasmic
- Cellular
- Cell/tissue
- Tissue/organ
- Organ system
They can aggregate to become multicellular

Porifera

sponges; sessile animals that lack true tissues; suspension feeders, trap particles that pass through the interal channels of their bodies.
They are the most basal animals.

Choanocytes

Collar cells that line the body cavity and have flagella that circulate water in sponges. Resemble Choanoflagellates

What are the first multicellular animals?

sponges

Diploblastic

System with a true body with tissues and organs. They have two germ layers; ectoderm and endoderm

Animal phylogeny order

Multicellularity - diploblastic - triplobastic - Protosomes (lopotrochozoa + Ecdysozoa) /Deterosomes

What are examples of diploblasts?

Cnidaria and Ctenophores

Characteristics of jellyfish and annemones

Diploblastic, no anus and myoepithal cells

comb jelly

Invertebrates that resemble jelly fishes and are the largest animals to be propelled by beating cilia.
They have a complete gut and muscle cells

triphloblastic

- Have all 3 germ layers: ecto- meso and endoderm
- they have a coelom
- Important advantage: more muscle layers are formed, so better mobility.

Types of body architectures

Acoelomate plan, Pseudocoelomate plan, Schizocoelus plan

Acoelomate plan

Mesodermal cells completely fill the blastocoel
Gut is only body cavity

spongy connective tissue

Pseudocoelomate plan

mesodermal cells line the outer edge of the blastocoel, leaving two body cavities: a persistent blastocoel and a gut cavity. No muscles around the gut!

blastocoel becomes pseudocoloem

Schizocoelus Plan

Band of mesoderm surrounds gut and splits open.

Protosomes vs Deuterostomes

Protostomes- blastopore forms the mouth first (Schizocoelus)
Deuterostomes- Blastopore forms the anus first (Enterocoelus). Deuterostomes can fall apart in development and still become the whole organism (think of twins)

stome

mouth

Lopotrochozoa

Group of protostomes: characterized by some animals having tenticles for filter feeding

Ecdysozoa

Supergroup of protostomes; characterized by periodic molting of their exoskeleton. Include the roundworms and arthropods.

Platyhelminthes

flatworms, part of lophotrochozoa, triploblast

Mollusca

(snails, clams, squids, octopuses) have a soft body that in many species is protected by a hard shell

part of lophotrochozoa, triploblast

Cephalopods

A member of a group of molluscs that include squids and octopus

Annelida

earthworm

Groups of Ecdysozoans

Arthropoda and Pancrustacea

Arthropoda

the phylum to which jointed-legged invertebrates belong, including insects, arachnids and crustaceans

Pancrustaceans

lobsters and other crustaceans, as well as insects and their relatives

Enchinodermata

Part of deuterostomes. Stekelhuidigen. Example is a starfish and seacucumbers

Hemichordata

Part of deuterosomes + Enchinodermata. Examples are kind of seaworms that feed by sucking in water and removing nutrients from it.

Spherical symmetry

An organism possesses spherical symmetry if it can be cut into two identical halves by any cut that runs through the organism's center

radial symmetry

body plan in which body parts repeat around the center of the body

biradial symmetry

body components are arranged with similar parts on either side of a central axis, and each of the four sides of the body is identical to the opposite side but different from the adjacent side

aboral

away from the mouth

Bilateria

animals with bilateral symmetry

Bilateral symmetry is strongly associated with...

cephalization, differentiation of a head.

frontal plane

Divides the body into front and back portions.

sagittal plane

divides body into left and right

transverse plane

horizontal division of the body into upper and lower portions

Pectoral

chest

Pelvic

pelvis region

segmentation in animals

refers to a body composed of a series of repeating similar units. Each segment is called a metamere, or somite.

advantage of segmentation

allows for specialization of body regions. It also facilitates locomotion

Development of a zygote in a triploblast

Triploblastic animals follow one of several major developmental pathways to form a blastula from a zygote. The most common pathways are by spiral or radial cleavage.

radial cleavage

A type of embryonic development in deuterostomes in that the planes of cell division that transform the zygote into a ball of cells are either parallel or perpendicular to the polar axis, thereby aligning tiers of cells one above the other.

spiral cleavage

A type of embryonic development in protostomes, in which the planes of cell division that transform the zygote into a ball of cells occur obliquely to the polar axis, resulting in cells of each tier sitting in the grooves between cells of adjacent tiers.

A coelom is made via

schizocoely.

Embryonal development, protosomes and deutrosomes

Protostomes
- Spiral mosaic cleavage,
- formation of the mouth from the blastopore,
- development of a coelom by schizocoely.

Deuterostomes:
- Radial regulative cleavage
- Formation of the anus from the blastopore
- Development of a coelom by enterocoely

Mosaic development is a result of

cytoplasmic differentiation. During cleavages, certain molecules divide unequally.

mosaic development

Pattern of animal embryonic development in which each blastomere contributes a specific part of the adult body.

Regulated cleavage

Each of the early blastomeres (such as that of a sea urchin) when separated from the others develops into a small pluteus larva.

pseudocoelom

body cavity between the endoderm and mesoderm tissues that is partially lined with mesoderm tissue

Lophotrochozoan protostomes

Triploblastic animals with bilateral symmetry, a blastopore becoming a mouth, and showing growth by incremental additions to the body

blastopore in deuterostomes

becomes anus

key stages phylogeny/evolution

single cell

multicelluler → cell differentiation (functions)

diploblast → gastrovascular cavity - ectoderm and endoderm

triploblast → formation archenteron - ectoderm, mesoderm and endoderm

quadruploblast → neural crest

eucoelomate

mesoderm fills blastocoel and then spliuts

mesoderm lines ectoderm and entoderm

true coeloom

protostomia

blastopore becomes mouth

deuterostomia

blastopore becomes anus, mouth forms secondarily

radial cleavage, regulative embryo