INTRODUCTION (copy)

**descriptive morphology**

structure of vertebrates

**ontogenesis**

development of the individual

**phylogenesis**

ancestral history

Zoology

animals

Histology

tissues

Genetics

* heredity, effects on variation and development

Paleontology

________- a historical record of past anatomy (fossils)

Embryology

________- from fertilization to parturition.

Evolution

natural selection and adaptation.

Ecology

________- organism- environment interactions.

Physics

________- angle of different bones.

Coelom

* Fluid-filled internal body cavity

Protostomes

* Includes molluscs, annelids, arthropods, and many smaller groups
* Divides into Lophotrochozoa and Ecysozoa

Deuterostomes

* Includes ambulacraria (echinoderms and hemichordates) and chorates

**cleavage**

* In both bilaterian groups, the egg begins to divide repeatedly after fertilization, a process termed **_______**, until the very young embryo is made up of many cells formed from the original single-celled egg. 

**spiral cleavage**

In some animals, dividing cells of the embryo are offset from each other, a pattern known as

**radial cleavage**

In others, the dividing cells are aligned, a pattern termed

**gastrulation**

One wall of this ball of cells begins to indent and grow inward, a process called

**blastopore**

The opening into this indentation is the __________*, and the indented cells themselves are destined to become the gut of the ad*ult.

Ectoderm

outer tissue layer

Endoderm

inner tissue layer that forms the lining of the gut

Mesoderm

* forms the layer between the two tissue layers

schizocoelom

If a solid mass of mesodermal cells splits to form the body cavity within them, the result is a

**Enterocoelom**

* If, instead, the mesoderm arises as outpocketings of the gut that pinch off to form the body cavity, the result is an **___________.**

Protostomes

Protostomes/Deuterostomes: First mouth

Deuterostomes

Protostomes/Deuterostomes: Second mouth

Protostomes

Protostomes/Deuterostomes: Blastopore(mouth)

Deuterostomes

Protostomes/Deuterostomes: Blastophore (anus)

Protostomes

Protostomes/Deuterostomes: Spiral Cleavage

Deuterostomes

Protostomes/Deuterostomes: Radial Cleavage

Protostomes

Protostomes/Deuterostomes: Schizocoelic coelom

Deuterostomes

Protostomes/Deuterostomes: Enterocoelic coelom

Protostomes

Protostomes/Deuterostomes: Ectodermal skeleton

Deuterostomes

Protostomes/Deuterostomes: Mesodermal skeleton

Phylogenetics

* study of mapping relationships between organisms.

Phylogenetic trees

branching diagrams that illustrate these relationships

Root

parts of phylogeny that refers to the common ancestor of all taxa

Node

parts of phylogeny that refers to the common ancestor of a smaller subset

branches

parts of phylogeny that refers to the descendants

Monophyletic

* **A single common ancestor and all of its descendants**

Paraphyletic

*  A common ancestor and some of its descendants

Polyphyletic

*  a grouping with no recent common ancestor

**Monophyletic**

* Well-known **___________** taxa include **Mammalia and Aves** (modern birds), recognizable as all furry and feathered vertebrates, respectively. 

Paraphyletic

___________ **taxa** include **Pisces and Reptilia,** the former comprising all ray-finned fish but excluding terrestrial descendants of fleshy-finned fish, and the latter comprising all scaly tetrapods but excluding mammals and birds with their modified scales.

Polyphyletic

____________________ taxa once in common usage include Agnatha for jawless lampreys and hagfish, and Insectivora for various toothless, insect-eating mammals such as anteaters and armadillos.

Chordates

* animals that have a notochord in the embryo stage at least. 

Craniates

 chordates with a neurocranium (braincase)

Vertebrates

Chordates with vertebrae

Notochord

a slender rod that develops from the mesoderm in all chordates.

vacuolated cells

The phylum takes the name Chordata from this structure. Typically, the notochord is composed of a core of cells and fluid encased in a tough sheath of fibrous tissue. Sometimes the fluid is held within swollen cells called ______________; other times it resides between core cells of the notochord.

Hydrostatic

* organ with elastic properties that resist axial compression. 

**nucleus pulposus**. 

In adult mammals with a full vertebral column, the notochord is reduced to a remnant, the

Head region

**Fate during development of ________________ is incorporated into skull floor**

Trunk and tail

**Fate during development of ________________ surrounded by cartilaginous or bony vertebrate**

**chief axial skeleton surrounded by notochord sheath**

**Fate of protochordates in adulthood**

**similar to protochordates with addition of lateral neural cartilages**

**Fate of** Agnathans **in adulthood**

persist the length of the trunk and tail within the centrum

Fate of Fishes and amphibians in adulthood

**disappears and becomes pulpy nucleus in mammal vertebrae**

Fate of **Reptiles, birds, and mammals**

Centrum

parts of vertebrae that is **deposited around notochord**

Neural arch

parts of the vertebrae that forms over spinal cord

Pharyngeal slits

part of the digestive tract located immediately posterior to the mouth.

**pharyngeal pouches**

During some point in the lifetime of all chordates, the walls of the embryonic pharynx push out into a series of bays, the **__________________**

**pharyngeal slits**

These may later nearly pierce, or in aquatic chordates actually pierce, the walls to form a longitudinal series of openings, the **____________** (also called **pharyngotremy)**

**pharyngeal or branchial basket**

In gill-less primitive chordates, the pharynx itself is often expanded into a **________________**, and the slits on its walls are multiplied in number, increasing the surface area exposed to the passing current of water.

**Sticky mucus lining**

* snatches food particles

Cilia lining

produce the water current

Permanent slits

Gills of fishes

Temporary slits

Lungs of tetrapods

**auditory and tympanic cavity**

Gives rise to middle ear cavity of tetrapods

Thymus

Provides initial cells of immune system during fetal life and shortly after

Pharyngeal arches

* a column of tissue which separates each embryonic pharyngeal pouch or slit from the next

External

type of indention where clefts lined with ectoderm

* Meckel’s cartilage
* Malleus
* Incus

Skeletal elements in arch 1

* Muscles of mastication
* Anterior belly of digastricus
* Tensor tympano
* Tensor palati

Muscles in arch 1

Trigeminal nerve (mandibular division)

Cranial nerve in arch 1

* Stapes
* Styloid process
* Upper part of hyoid

Skeletal elements in arch 2

* Stapedius
* Stylohyoid
* Muscles of facial expression
* Posterior belly of digastricus

Muscles in arch 2

Facial nerve

Cranial nerve in arch 2

Lower part of hyoid

Skeletal elements in arch 3

Stylopharyngeus

Muscles in arch 3

Glossopharyngeal nerve

Cranial nerve in arch 3

Laryngeal cartilages

Skeletal elements in arches 4-6

* Cricotyhroideus
* Pharyngeal contrictors
* Intrinsic laryngeal muscles

Muscles in arches 4-6

Vagus nerve

Cranial nerve in arches 4-6

Pharyngeal skeleton

supportive skeletal elements

Branchiomeric muscles

Striated muscles that operate the arch

Cranial nerves

innervate muscles and provide sensory input to the brain.

Aortic arch

connects the ventral and dorsal aortas.

Pharyngeal pouches

* Arises as diverticula of endoderm or foregut
* Grows toward the surface of the animal 
* Establish the limits of the pharynx

8

Maximum number in jawed craniates of basal shark

15

Maximum number in jawed craniates of living agnathans

* Middle ear cavity
* Endodermal aspect of tympanic membrane
* Pharyngotympanic tube

Pharyngeal pouch 1

Palatine tonsil

Pharyngeal pouch 2

* Inferior parathyroid gland
* Thymus

Pharyngeal pouch 3

* Superior parathyroid gland
* Parafollicular cells of the thyroid gland

Pharyngeal pouch 4 and 5

Pharyngeal slits

* formed between the pharynx and the exterior when the pharyngeal plate ruptures. 

Endostyle

* glandular groove in the floor of the pharynx. 

Thyroid gland

* **endocrine gland that produces two major hormones.**

Dorsal and tubular nerve cord

* derived from ectoderm

**invagination**

* The central nervous system of all animals is ectodermal in embryonic origin, but only in chordates does the nerve tube typically form by a distinctive embryonic process, namely, by **___________**.