Ch. 32 - Animal Diversity
lophotrochozoa
one of the three main lineages of bilaterian animals have lophophore have only invertebrates
deuterostomia
one of the three main lineages of bilaterian animals include acorn worms & sea stars doesn't mean animals who have deuterostome are part of this clade
phylum chordata
only phylum that has vertebrate members also has invertebrates
bilaterian
member of a clade of animals with bilateral symmetry and 3 germ layers complete digestive tract most of the fossils from the cambrian explosion are from here___ (molliscs, arthropods, chordates, and most other living animal phyla)
Neoproterozoic Era
molecular evidence for multicellular animal The end of the ___ was during an increase in animal diversity this geologic era took place 1 billion to 542 million years ago
Animal Kingdom Origin
Choanoflagellates are closely related to animals - DNA seq. data - Morphologically indistinguishable - similar collar cells found in other animal but not in non-choanoflagellate protists, plants, or funi
trochopore larva
distinctive larval stage observed in some lophotrochozoan animals, including some annelids and molluscs
Characteristics of animals
eukaryotes multicellular structural support = proteins external to the cell membrane (collagen) cells organized into tissues muscle and nerve cells (allow motility)
cleavage
(1) The process of cytokinesis in animal cells, characterized by pinching of the plasma membrane. (2) The succession of rapid cell divisions without significant growth during early embryonic development that converts the zygote to a ball of cells.
Body Cavities (coelom)
- Cushions internal organs - In some, internal skeleton - Allows independent growth & movement of internal organs
Characteristics of animals
1) All animal share a common ancestor - monophyletic 2) Sponges are basal animals 3) Eumetazoa is a clade of animals with true tissues 4) most animal phyla belong to the clade bilateria 5) there are 3 major clades of bilaterian animals - deuterostomia, lophotrochozoa, ecdysozoa
3 lines of evidence that choanoflagellates are closely related to animals
1) Morphologically, choanoflagellate cells and the collar cells of sponges are almost indistinguishable 2) Similar collar cells have been identified in other animals, but they have never been observed in non-choanoflagellate protists or in plants or fungi 3) DNA sequence data indicate that they and animals are sister groups. Genes for signaling and adhesion proteins previously known only from animals have been discovered in them
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
Body plans differentiated by
1.Body symmetry 2.Tissue organization 3.Body cavity -Present •Type -Absent 4.Mode of development A group of animal species with the same level of organizational complexity is called a "GRADE"
Arthropod
1st animals to adapt to terrestrial habitats
diploblastic
2 germ layers
Mesozoic Era
251 - 65.5 million years ago age of reptiles (dinosaurs, small mammals); extinction of dinosaurs at end animals spreading to new habitats
triploblastic
3 germ layers All bilaterian animals are _____ Ex: flatworms, arthropods, vertebrates
Cenozoic Era
65.5 million yrs ago mass extinction of both terrestrial and marine animals (dinosaurs, marine reptiles) rise of large mammalian herbivores and predators global climate gradually cooled, trigger shift in animal lineages
Endoderm
gives rise to lining of digestive tract
Mesoderm
gives rise to muscles and most other organs between the digestive tract (or gut) and the outer covering of the animal.
Ectoderm
gives rise to the outer covering of the animal.
grade
group whose members share key biological features not equivalent to clade
Life Cycle of animals
Most animals have life cycles with larval stages which undergo metamorphosis to an adult stage Larval stage is often the feeding/dispersal stage - May be longest stage
mesoderm
One of the three primary (embryonic) germ layers formed during gastrulation. ultimately forms 'middle' structures such as bones, muscles, blood vessels, heart, kindeys, etc.
Body symmetry
Oral (top) & aboral (bottom) only Body symmetry fits lifestyle Anterior (front, head end) Posterior (back, tail end)
triploblastic
Protostome and deuterostomes are tripoblastic, diploblastic, or neither?
Hox genes
Regulate development of body form Animals have unique set of regulatory genes
B) The oldest generally accepted fossils of large animals range in age from 565 to 550 million years old. Not A bc says ORGANISMS and is supposed to be ANIMALS
Select the correct statement about the evolution of animals. Select the correct statement about the evolution of animals. A) Approximately half the phyla of living organisms are found in Cambrian sediments. B) The oldest generally accepted fossils of large animals range in age from 565 to 550 million years old. C) No animal fossils are found in strata formed before the Cambrian explosion.
C) Development in all animals is determined by the unique family of Hox genes (or other similar homeobox genes). Not A bc acoelomates are triploblastic
Select the correct statement(s) about animal body plans. A) All triploblastic animals possess a coelom. B) In both protostomes and deuterostomes, the blastopore develops into the mouth. C) Development in all animals is determined by the unique family of Hox genes (or other similar homeobox genes).
true tissues
The distinction bw sponges and other animal phyla is based MAINLY on the absence versus the presence of
metamorphosis
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. used for cushioning of organs, prevent internal injury
larva
A free-living, sexually immature form in some animal life cycles that may differ from the adult in morphology, nutrition, and habitat.
- Look for cell walls under a microscope. BC fungus have cell walls made up of chitin and humans have none
A graduate student finds an organism in a pond and thinks it is a freshwater sponge. A postdoctoral student thinks it looks more like an aquatic fungus. How can they decide whether it is an animal or a fungus? - Look for cell walls under a microscope. - Determine whether it is unicellular or multicellular. - Figure out whether it is autotrophic or heterotrophic. - See if it is a eukaryote or prokaryote. - See if it reproduces sexually.
blastula
A hollow ball of cells that marks the end of the cleavage stage during early embryonic development in animals.
Cambrian Explosion
A relatively brief time in geologic history when large, hard-bodied forms of animals with most of the major body plans known today appeared in the fossil record. This burst of evolutionary change occurred about 535-525 million years ago (Paleozoic Era). oldest fossils of about half of all extant animal phyla (arthropods, chordates, echinoderms)
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.
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.
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.
gastrulation
Among the characteristics unique to animals is?
d. has an aggregation of sensory
An important trend in animal evolution was cephalization. An animal is said to show cephalization when it _____. a. has bilateral symmetry b. has tissue specialization c. is large d. has an aggregation of sensory neurons at the anterior end e. has a hard, outer covering
A diploblast has no mesoderm. A pseudocoelom has the same functions as a true coelom. In a coelomate, the tissue lining the inner side of the body cavity arises from the same germ layer as the tissue lining the outer side of the body cavity.
Animal tissues develop from embryonic germ layers. Triploblastic animals have three germ layers (ectoderm, mesoderm, and endoderm) and three basic body plans related to body cavities (acoelomate, pseudocoelomate, and coelomate). Select the three statements that are true. To review the germ layers and the terminology associated with body cavities, see the Hints. A diploblast has no mesoderm. A pseudocoelom has the same functions as a true coelom. In a coelomate, the tissue lining the inner side of the body cavity arises from the same germ layer as the tissue lining the outer side of the body cavity. The digestive tract of a coelomate functions as a coelom. An acoelomate triploblast has no endoderm. In a coelomate, the tissue lining the inner side of the body cavity arises from the same germ layer as the lining of the digestive tract. In a pseudocoelomate, the tissue lining the inner side of the body cavity arises from the same germ layer as the muscles.
Early embryonic development
Animal tissues develop from embryonic layers Animals may be diploblastic or triploblastic
invertebrates
Animals without backbones, 95% of animal species
not yet known, but if they were ancetor would have to have a simple nervous system, saclike gut w/ single opening, and no excretory syst
Are acoelomate flatworms basal bilaterians?
still a hypothesis bc have true tissues and don't resemble cells of choanoflagellates
Are ctenophores basal metazoans?
yes, but were once thought to be paraphyletic
Are sponges monophyletic (single phylum)?
Acoelomate flatworms are more closely related to echinoderms than to annelids. bc they are EQUALLY related
Based on the tree in Figure 32.11, which statement is false?
coelomate
Body cavity lined entirely by mesoderm-derived tissue
pseudocoelomate
Body cavity lined on the inner side by endoderm-derived tissue and on the outer side by mesoderm-derived tissue
bilateral symmetry
Body symmetry in which a central longitudinal plane divides the body into 2 equal but opposite halves may have sensory equipment in anterior end, include CNS move fast and are active All are triploblastic
HUMANS
During embryological development, the anus forms before the mouth in _____. - arthropods - humans - flatworms - earthworms - slugs
Tissues are formed by germ layers
Ectoderm - Outer coverings - Sometimes CNS Mesoderm - Muscle - Most organs between digestive tract & outer covering Endoderm - Digestive tract lining - Some organs -- Liver, lungs
Kingdom Animalia
Eukaryotic - lack cell walls Multicellular - Unique intercellular junctions Common set of ECM molecules - Includes collagen, - proteoglycans.. have unique cells and tissues
- Animals are ingestive heterotrophs.
Identify the features that distinguish animals from organisms in other multicellular kingdoms. Select all that apply. - Animals are motile. - Animals have sensory organs at their anterior end. - Animals are ingestive heterotrophs.
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.
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 most are interdeterminate cleavage
body plan
In animals, a set of morphological and developmental traits that are integrated into a functional whole—the living animal.
protosome development
In animals, 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. most are determinate cleavage
Nutrition mode of Kingdom Animalia
Ingestive heterotrophs - Digest, absorb nutrients within body
eumetazoans
Member of a clade of animals with true tissues. All animals except for sponges
archenteron
The endoderm-lined cavity, formed during the gastrulation process, that develops into the digestive tract of an animal.
blastopore
The opening of the archenteron in the gastrula that develops into the mouth in protostomes and the anus in deuterostomes
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. CNS in some animals
- Deuterostomes have indeterminate development. BC retain the capacity to develop into a complete embryo
Which feature of deuterostome development explains the formation of identical human twins? - Deuterostomes have radial cleavage. - Deuterostomes have indeterminate development. - In deuterostomes, the blastopore becomes the anus
- the movement of animals onto land
Which of the following was probably the least important factor in bringing about the Cambrian explosion? - the emergence of predator-prey relationships among animals - the accumulation of diverse adaptations, such as shells and different modes of locomotion - the movement of animals onto land - the evolution of Hox genes that controlled development - the accumulation of sufficient atmospheric oxygen to support the more active metabolism of mobile animals
Cleavage Pattern
With indeterminate cleavage, cells retain totipotency
totipotency
ability of a cell to direct development of an organism
coelomates
an animal that posses a true coelom (body cavity lined by tissue completely derived from mesoderm) have internal organs Ex: Earthworm
Ediacaran Biota
an early group of macroscopic, soft-bodied, multicellular eukaryotes known from fossils that rand in age from 635 million to 535 million years ago.
vertebrates
animals with backbones
pseudocoelomates
body cavity is lined by tissue derived from mesoderm and endoderm NOT FULLY LINED W/ MESODERM Ex: roundworms
Ecdysozoa
characteristics shared by nematodes, arthropods, and some others one of the three main lineages of bilaterian animals have only invertebrates exoskeleton molts
lophophore
in some lophotrochozoan animals, including brachiopods, a crown of ciliated tentacles, that surround the mouth and function in feeding
endoderm
innermost germ layer; develops into the linings of the digestive tract (archenteron) and much of the respiratory system
tissues
integrated group of cells with a common structure, function, or both
Hypotheses of declined edicaran after cambrian explosion
predator-prey relationship (natural selection) atmospheric changes changes in development (genetic variation)
Reproduction of animals
reproduce sexually diploid stage dominates life cycle
ecdysis
shedding of old exoskeleton
acoelomates
solid-bodied animal lacking a cavity between the gut and outer body wall Ex: Planarians
radial symmetry
symmetry in which body is shaped like a pie or barrel (lacking a left side and a right side) and can be derived into mirror-imaged halves by any plane through its central axis sessile (living attached to a substrate) planktonic (drifting or weakly swimming, Ex: jellies)
