Chap 32

which of cladograms shown below match the traits?

1 and 4

Paleozoic Era (541-252 Million Years Ago

Another wave of animal diversification -the Cambrian explosion ( explosion are of bilaterians) -movement to land

lophotrochozoa

One of the three main lineages of bilaterian animals; lophotrochozoans include organisms that have lophophores or trochophore larvae. See also Deuterostomia and Ecdysozoa.

anterior

Pertaining to the front, or head, of a bilaterally symmetrical animal.

posterior

Pertaining to the rear, or tail end, of a bilaterally symmetrical animal.

dorsal

Pertaining to the top of an animal with radial or bilateral symmetry.

Asymmetry -

a body plan that lacks symmetry - Ex: sponges because they have no tissue organization.

larva

(plural, larvae) A free-living, sexually immature form in some animal life cycles that may differ from the adult animal in morphology, nutrition, and habitat.

Triploblastic

- contains endoderm, mesoderm, and ectoderm in the embryo -the mesoderm forms the muscles and most other organs between the digestive tract and the outer covering of the animal. -includes a broad range of animals, from flatworms to arthropods to vertebrates. -can be coelomates, pseudocoelomates, or acoelomates -Most triploblastic animals have a body cavity

Diploblastic

- contains only endoderm and ectoderm -(Although some diploblasts actually do have a third germ layer, it is not nearly as well developed as the mesoderm of animals considered to be triploblastic.)

Deuterostomia characteristics

- radial pattern of cleavage - The cleavage planes are either parallel or perpendicular to the vertical axis of the embryo; as seen at the eight-cell stage, the tiers of cells are aligned, one directly above the other - also does indeterminate cleavage (stem cells) - cells are the same size - the mesoderm buds from the wall of the archenteron, and its cavity becomes the coelom. -Fate of the Blastopore: In deuterostome development (from the Greek deuteros, second), the mouth is derived from the secondary opening, and the blastopore usually forms the anus. -coelum from folds of archenteron - Tripoblast -humans

Protostome charateristics

- spiral pattern of cell division (spiral cleavage) - determinate cleavage (less advantageous because if you lose a cell it cannot be replaced) - By the time they get to about the four-cell stage, the cells have lost their totipotency and their fate is already fixed. - cells of different sizes (as seen in the eight-cell stage of the embryo, smaller cells are centered over the grooves between larger, underlying cells) -As the archenteron forms in protostome development, initially solid masses of mesoderm split and form the coelom. - Fate of the Blastopore: the mouth generally develops from the first opening, the blastopore, and it is for this characteristic that the term protostome derives (from the Greek protos, first, and stoma, mouth). -triploplast -molusc

As was the case with symmetry there are three possible configurations with respect to a body cavity:

-Coelomates - Where the cavity is derived from mesoderm - coelom opens up within the mesoderm as development is happening -Pseudocoelomates - Where a cavity is present but is not derived from the mesoderm. -Acoelomates - No coelom

An Overview of Animal Diversity The main distinguishing features of the Kingdom Animalia are

-Eukaryotic -Multicellular -Heterotrophic -Ingestive method of digestion -Sexual reproduction -No cell wall -Rapid response to stimuli (nerves and muscles)

Cenozoic Era (66 Million Years Ago to the Present)

-Mass extinctions of both terrestrial and marine animals ushered in this new era -groups of species that disappeared were the large, nonflying dinosaurs and the marine reptiles. -rise of large mammalian herbivores and predators as mammals began to exploit the vacated ecological niches. - The global climate gradually cooled throughout this era triggering significant shifts in many animal lineages.

Organs may then become arranged into organ systems:

-Tissues are specialized cells with a common structure and function that are grouped together. -Organs are centers of bodily function, which are usually made up of different tissues. -Organ systems are groups of two or more organs that function together to perform a common task (e.g., digestion, gas exchange, reproduction)

Which of the following cladograms gives the best possibly match to the traits?

1

the species that is the most distantly related to species 2 is species

1

Early embryonic development in animals

1) Zygote of an animal undergoes a series of mitotic cell division called cleavage 2) 8-celled embryo is formed by 3 rounds of cell division 3) in most animals, cleavage produces a multicellular stage called a blastula (hollow ball of cells that surround a cavity called the blastocoel) 4) Most animals undergo gastrulation, process in which one end of the embryo folds inward, expands, and eventually fills the blastocoel, producing layers of embryonic tissues; ectoderm and endoderm 5) pouch formed by gastrulation, called archenteron, opens to the outside via the blastospore 6) endoderm of the archenteron develops into the tissue lining the animal's digestive tract

Future Directions in Animal Systematics

1. ARE SPONGES MONOPHYLETIC? (probably) 2. ARE CTENOPHORES BASAL METAZOANS? 3. ARE ACOELOMATE FLATWORMS BASAL BILATERIANS?

The Diversification of Animals

1. All animals share a common ancestor. (monophyletic, forming a clade called Metazoa) 2. Sponges are basal animals. 3. Eumetazoa is a clade of animals with true tissues.(All animals except for sponges and a few others belong to this clade) 4. Most animal phyla belong to the clade Bilateria.(bilateral symmetry and the presence of three prominent germ layers are shared derived characters that help define the clade Bilateria.) 5. There are three major clades of bilaterian animals. (Deuterostomia, Lophotrochozoa, and Ecdysozoa. With one exception, the phyla in these clades consist entirely of invertebrates, animals that lack a backbone; Chordata is the only phylum that includes vertebrates, animals with a backbone.)

data from fossil steroids and molecular clocks indicate ___ as the time of origin, the first generally accepted macroscopic fossils of animals date from about___

710 milion years ago, 560 million years ago

coelom

A body cavity lined by tissue derived only from mesoderm.

vertebrate

A chordate animal with vertebrae, the series of bones that make up the backbone.

metamorphosis

A developmental transformation that turns an animal larva into either an adult or an adult-like stage that is not yet sexually mature.

body cavity

A fluid- or air-filled space between the digestive tract and the body wall.

blastula

A hollow ball of cells that marks the end of the cleavage stage during early embryonic development in animals. -3

standard deviation

A measure of the variation found in a set of data points.

bilaterian

A member of a clade of animals with bilateral symmetry and three germ layers. -most of the fossils from the Cambrian explosion -enormous clade whose members (unlike sponges and cnidarians) typically have a two-sided or bilaterally symmetric form and a complete digestive tract, an efficient digestive system that has a mouth at one end and an anus at the other. -includes molluscs, arthropods, chordates, and most other living animal phyla.

eumetazoan

A member of a clade of animals with true tissues. All animals except sponges and a few other groups are eumetazoans.

cambrian explosion

A relatively brief time in geologic history when many present-day phyla of animals first appeared in the fossil record. This burst of evolutionary change occurred about 535-525 million years ago and saw the emergence of the first large, hard-bodied animals.

acoelomate

A solid-bodied animal lacking a cavity between the gut and outer body wall.

indeterminate cleavage

A type of embryonic development in deuterostomes in which each cell produced by early cleavage divisions retains the capacity to develop into a complete embryo.

radial cleavage

A type of embryonic development in deuterostomes in which the planes of cell division that transform the zygote into a ball of cells are either parallel or perpendicular to the vertical axis of the embryo, 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 are diagonal to the vertical axis of the embryo. As a result, the cells of each tier sit in the grooves between cells of adjacent tiers.

determinate cleavage

A type of embryonic development in protostomes that rigidly casts the developmental fate of each embryonic cell very early.

Fate of the Blastopore Protostome and deuterostome development often differ in the fate of the blastopore, the indentation that during gastrulation leads to the formation of the archenteron

After the archenteron develops, in most animals a second opening forms at the opposite end of the gastrula. In many species, the blastopore and this second opening become the two openings of the digestive tube: the mouth and the anus. -In protostome development, the mouth generally develops from the first opening, the blastopore, and it is for this characteristic that the term protostome derives (from the Greek protos, first, and stoma, mouth). -In deuterostome development (from the Greek deuteros, second), the mouth is derived from the secondary opening, and the blastopore usually forms the anus.

coelomate

An animal that possesses a true coelom (a body cavity lined by tissue completely derived from mesoderm).

pseudocoelomate

An animal whose body cavity is lined by tissue derived from mesoderm and endoderm. -Despite its name, however, a pseudocoelom is not false; it is a fully functional body cavity.

invertebrate

An animal without a backbone. Invertebrates make up 95% of animal species.

ediacaran biota

An early group of macroscopic, soft-bodied, multicellular eukaryotes known from fossils that range in age from 635 million to 535 million years old. -earliest known macroscopic animals, including these two species.

gastrula

An embryonic stage in animal development encompassing the formation of three layers: ectoderm, mesoderm, and endoderm.

tissue

An integrated group of cells with a common structure, function, or both.

__ were the first animals to adapt to terrestrial habitats

Arthropods

Three possible arrangements are seen:

Asymmetry, radial symmetry, and bilateral symmetry

bilateral symmetry

Body symmetry in which a central longitudinal plane divides the body into two equal but opposite halves.

Describe the evidence that cnidarians share a more recent common ancestor with other animals than with sponges.

Cnidarians possess tissues, while sponges do not. Also unlike sponges, cnidarians exhibit body symmetry, though it is radial and not bilateral as in most other animal phyla.

trochophore larva

Distinctive larval stage observed in some lophotrochozoan animals, including some annelids and molluscs.

Coelom Formation

During gastrulation, an embryo's developing digestive tube initially forms as a blind pouch, the archenteron, which becomes the gut -As the archenteron forms in protostome development, initially solid masses of mesoderm split and form the coelom. -In contrast, in deuterostome development, the mesoderm buds from the wall of the archenteron, and its cavity becomes the coelom.

diploblastic

Having two germ layers.

blastopore

In a gastrula, the opening of the archenteron that typically develops into the anus in deuterostomes and the mouth in protostomes.

gastrulation

In animal development, a series of cell and tissue movements in which the blastula-stage embryo folds inward, producing a three-layered embryo, the gastrula. -during which the layers of embryonic tissues that will develop into adult body parts are produced - The resulting developmental stage is called a gastrula - 4

deuterostome development

In animals, a developmental mode distinguished by the development of the anus from the blastopore; often also characterized by radial cleavage and by the body cavity forming as outpockets of mesodermal tissue.

protostome development

In animals, a developmental mode distinguished by the development of the mouth from the blastopore; often also characterized by spiral cleavage and by the body cavity forming when solid masses of mesoderm split.

body plan

In multicellular eukaryotes, a set of morphological and developmental traits that are integrated into a functional whole—the living organism.

lophophore

In some lophotrochozoan animals, including brachiopods, a crown of ciliated tentacles that surround the mouth and function in feeding.

Eras and periods in this chapter

Neoproterozoic Era (1 Billion-541 Million Years Ago) - Ediacaran period (635-541 million years ago) Paleozoic Era (541-252 Million Years Ago) Mesozoic Era (252-66 Million Years Ago) Cenozoic Era (66 Million Years Ago to the Present)

deuterostomia

One of the three main lineages of bilaterian animals. See also Ecdysozoa and Lophotrochozoa.

ecdysozoa

One of the three main lineages of bilaterian animals; many ecdysozoans are molting animals. See also Deuterostomia and Lophotrochozoa.

ventral

Pertaining to the underside, or bottom, of an animal with radial or bilateral symmetry.

triploblastic

Possessing three germ layers: the endoderm, mesoderm, and ectoderm. All bilaterian animals are triploblastic.

Types of cleavage patterns

Spiral/determinate cleavage vs. Radial/indeterminate cleavage

radial symmetry

Symmetry in which the body is shaped like a pie or barrel (lacking a left side and a right side) and can be divided into mirror-imaged halves by any plane through its central axis.

Mesozoic Era (252-66 Million Years Ago)

The animal phyla that had evolved during the Paleozoic now began to spread into new habitats -dinosaurs emerged -the first mammals -flowering plants (angiosperms) and insects both underwent dramatic diversifications during the late Mesozoic.

archenteron

The endoderm-lined cavity, formed during gastrulation, that develops into the digestive tract of an animal. - 5 and 6

endoderm

The innermost of the three primary germ layers in animal embryos; lines the archenteron and gives rise to the liver, pancreas, lungs, and the lining of the digestive tract in species that have these structures.

mesoderm

The middle primary germ layer in a triploblastic animal embryo; develops into the notochord, the lining of the coelom, muscles, skeleton, gonads, kidneys, and most of the circulatory system in species that have these structures.

ectoderm

The outermost of the three primary germ layers in animal embryos; gives rise to the outer covering and, in some phyla, the nervous system, inner ear, and lens of the eye.

Explain what is represented by the red-colored portion of the branch leading to animals.

The red-colored portion of the tree represents ancestors of animals that lived between 1 billion years ago and 770 million years ago. Although these ancestors are more closely related to animals than to fungi, they would not be classified as animals. One example of an ancestor represented by the red-colored portion of this tree is the most recent common ancestor shared by choanoflagellates and animals.

cleavage

The succession of rapid cell divisions without significant growth during early embryonic development that converts the zygote to a ball of cells. - a succession of mitotic cell divisions without cell growth between the divisions - leads to the formation of a multicellular embryonic stage called a blastula - 1, 2, and 3

mean

The sum of all data points in a data set divided by the number of data points.

One type of body plan is based on presence and type of symmetry. Symmetry incicates that

a geometric plane could be drawn through an organisim such that the halves of the organisim are mirror images of each other.

the origin of multicellularity requires the evolution of new ways for cells to

adhere (attach) and signal (communicate) to each other.

cadherin

attachment proteins -evidence of choanoflagellates being closely related to animals - DNA sequence analyses show that animal cadherin proteins are composed primarily of domains that are also found in a cadherin-like protein of choanoflagellates -however, animal cadherin proteins also contain a highly conserved region not found in the choanoflagellate protein (the "CCD" domain)

in a phylogenetic tree, a lineage that diverges from all other members of its group early in the evolutionary history of the group is described as

basal taxon

Another body plan feature is the presence of a body cavity known as a coelom. Many animals with bilateral symmetry also have some type of coelom. Coelom is the

body cavity that is between the digestive system and the body wall - Shows up in a pattern in the animal kingdom that does not suggest phylogenetic history. (can't base the phylogenetic tree on it)

Bilateral symmetry -

body plan with a left side and a right side. (see fig 32.8b) - Triploblastic - Also means a top (dorsal), bottom (ventral), front/head (anterior) and back/tail (posterior) surface can be determined

Animals can be characterized by

body plan.

Put the following milestones in animal evolution in order from oldest to most recent: (a) origin of mammals, (b) earliest evidence of terrestrial arthropods, (c) Ediacaran fauna, (d) extinction of large, nonflying dinosaurs.

cbad Ediacaran fauna earliest evidence of terrestrial arthropods origin of mammals extinction of large, nonflying dinosaurs.

Another of the difference which occurs during embryonic development is based on

cleavage patterns and whether the cell future is fixed or variable. These modes can generally be distinguished by differences in cleavage, coelom formation, and fate of the blastopore. This is one of the differences that separate protostomes and deutrostomes (see fig 32.10)

Tissue level organization of a body plan develops directly from

embryonic layers of cells

The three possible germ layers are:

endoderm - interior lining of the organs - the digestive system and anything that buds off of it mesoderm - middle - muscles, skeleton and circulatory system ectoderm - outer coverings - skin, hair fingernails, eyes, ears

___ and ___ are members of the bilaterian clade Deuterostomia; thus, the term deuterostome refers not only to a mode of animal development, but also to the members of this clade. (The dual meaning of this term can be confusing since some organisms with a deuterostome developmental pattern are not members of clade Deuterostomia.

hemichordates (acorn worms), echinoderms (sea stars and relatives), and chordates

developmental genes that regulate the expression of other genes, and many of these regulatory genes contain sets of DNA sequences called

homoboxes

In the early embryo (see fig 32.2) there are differences in

how different linages in the animal kingdom develop.

Sponges lack __ but they do have ___ such as ___

hox genes, other homeobox genes that influence their shape, such as those that regulate the formation of water channels in the body wall.

As the diversity of animal phyla increased during the Cambrian, the diversity of Ediacaran life-forms declined. Why

hypothesis: -As new predator-prey relationships emerged, natural selection may have led to the decline of the soft-bodied Ediacaran species and the rise of various bilaterian phyla -an increase in atmospheric oxygen that preceded the Cambrian explosion. More plentiful oxygen would have enabled animals with higher metabolic rates and larger body sizes to thrive, while potentially harming other species. -genetic changes affecting development, such as the origin of Hox genes and the addition of new microRNAs facilitated the evolution of new body forms

in animals during the haploid stage, sperm and egg cells are produced directly by

meiotic division

In addition to these characteristics, as animals evolved from the animal-like protists, they developed

more complex and organized bodies.

Embryonic development is the precursor to

more complex body plans

A phylogeny of living animals

only one phylum (Chordata) contains vertebrates; the rest are invertebrates -This phylogeny shows a leading hypothesis about the relationships among selected animal phyla. The bilaterians are divided into three main lineages: deuterostomes, lophotrochozoans, and ecdysozoans. The dates of origin identified here are based on the results of a recent molecular clock study.

Historically the linages in the animal kingdom were arranged in a

phylogeny based of morphological and developmental characteristics. The availability of molecular data is changing the phylogenetic arrangement for some of the animal kingdom (see fig 32.11)

The closest relative to the animals are

protists in the clade known as opisthokonts (see fig 32.3) - choanoflagellates

Radial symmetry -

round body plan (see fig 32.8a) - Diploblastic - Circular/ cylindrical body plan - Animals have a top and bottom but no back/front or left/right. - Two layers in their embryonic development

Hox genes

series of genes that controls the differentiation of cells and tissues in an embryo and play important roles in the development of animal embryos, controlling the expression of many other genes that influence morphology -homeobox-containing family of genes - this gene family arose via the duplication of earlier homeobox genes - Over time, this gene family underwent a series of duplications, yielding a versatile "toolkit" for regulating development - In most animals, these genes regulate the formation of the anterior-posterior (front-to-back) axis

Many radial animals are ____ or ____.

sessile (living attached to a substrate) or planktonic (drifting or weakly swimming, such as jellies, commonly called jellyfishes).

microRNAs

small RNAs involved in gene regulation

Out group for the animal kingdom

sponges (Porifera) (no true tissues)

Cellular specialization leads to

the development of tissues, which then can lead to the combination of tissues into an organ.

Bilaterians also diversified in two major clades that are composed entirely of invertebrates:

the ecdysozoans (ecrete external skeletons (exoskeletons) and the lophotrochozoans. (Some develop a unique structure called a lophophore)

Some of these differences arise as early as ____. Other differences between linages occur at _____.

the eight-cell stage, the gastrulation stage

Neoproterozoic Era (1 Billion-541 Million Years Ago) - Ediacaran period (635-541 million years ago)

the first generally accepted macroscopic fossils of animals -The fossil record from the Ediacaran period (635-541 million years ago) also provides early evidence of predation.

The presence or absence of tissues in an organism defines

the first separation of a group from the rest of the animals.

Germ layers are

the layers of cells in the early embryo that lead to all tissues and organs. -Diploblastic vs. Triploblastic

Terms such as coelomates and pseudocoelomates refer to organisms that have a similar body plan and hence belong to ___, however,

the same grade ,(a group whose members share key biological features). However, phylogenetic studies show that true coeloms and pseudocoeloms have been independently gained or lost multiple times in the course of animal evolution.

(TF) The 2 cladograms represent a different evolutionary pattern they are not just drawn differently.

true

The 2 cladograms represent the same evolutionary pattern they are just drawn differently.

true

the most ancient branch point in animal phylogeny is the characteristic of having _____.

true tissues or no true tissues

Cellular specialization or partnership between specialized cells may have been

what ultimately lead to the animal kingdom. - cells have an inter reliance on one another. - this leads to cellular specalization