Flashcards in Lecture 1 Deck (49)
List the three subphyla of the phylum Chordata
Cephalochordata, Urochordata, Vertebrata
Describe the major characteristics of cephalochordates
Notochord located in the cranial "head", represented by lancelets (amphioxus)
Describe the major characteristics of urochordates
Represented by sea squirts (ascidians), they develop as larva with dorsal notochords, but lose them upon maturation when they reach their immobile adult phase. Body cavities are only loosely definable.
Describe the major characteristics of vertebrates
Notochord develops into vertebral column - represented by the classes pisces, and tetrapods
List the five classes grouped into the Pisces Supergroup
Agnatha, Acanthodii, Placodermi, Chondrichthyes, and Osteichthyes
Describe the major characteristics of Agnatha
These fish lack jaws or paired appendages. Examples include the hagfish and possibly lampreys.
Describe the major characteristics of acanthodii.
An extinct class which used to include spiny sharklike creatures that were possibly the first vertebrates to have jaws (gnathostomes). They share this characteristic with placoderms
Describe the major characteristics of placoderms
An extinct class of gnathostomes (first jawed fish) who first developed paired fins. Ranged from very small to very large.
Describe the major characteristics of chondrichthyes
Class of fish unable to form bone, but developed skeletal systems made of cartilage. Includes both extinct and extant sharks, and rays.
Describe the major characteristics of osteichthyes
Largest current class of fish species, includes any fish with bone skeletal structures (though some can still retain some cartilage)
Name the four classes of tetrapods
Amphibia, Reptilia, Aves, and Mammalia
Describe the characteristics/examples of amphibia
Includes both extinct and extant amphibians including frogs, toads, and salamanders.
Describe the characteristics/examples of reptilia
Includes extinct and extant lizards, snakes, turtles, crocodiles, and dinosaurs (including flying reptile such as pterosaurs)
Describe the characteristics/examples of aves
Birds, both extinct and extant. Major characteristic is the presence of feathers.
Describe the major characteristics/examples of mammalia
Extinct and extant mammals, had both hair and mammary glands
List the four anatomical features all chordates possess
(Embryological) Dorsal Hollow Nerve Cord, Pharyngeal slits arches and pouches, a notochord, and a post-anal tail.
List four features of the dorsal hollow nerve cord.
1. Represents future brain and spinal cord
2. Hollow tube that runs dorsal to the notochord
3. Retained as adults in vertebrates as the hollow space in brain and spinal canal
4. Can comprise of entire nervous system in some invertebrates
Where is the pharynx located and what is the purpose of pharyngeal pouches
Pharynx is in Cranial portion of the gut tube. The pouches connect exterior of the organism with the interior of the pharynx, and are often retained after maturation as gill slits,
What are pharyngeal arches and where are they found?
The area between pharyngeal pouches are called arches. These each contain a skeletal element, branchiomeric muscles, cranial nerves, and an aortic arch. The first arch is called the Mandibular arch (gills, auditory tubes, middle ear cavities) and the second arch is called the hyoid arch (forms the palate tonsils in mammals)
What were the primitive original purposes of the pharynx in regard to respiration
Though originally for filter feeding by trapping plankton, the pharynx developed external gills from the pharyngeal pouch, which subsequently developed vascularization that allowed oxygen to be extracted from the water flowing through these gill slits.
What is the notochord and what purpose does it serve
The notochord runs ventral to the nerve cord and dorsal to the gut tube and is a hollow tube made of cells resembling (but not matching) cartilage. In embryos it provides hydrostatic support in water (damage during this stage is usually devastating), but it continues to provide axial skeletal support in agnathans.
In mammals, what becomes of the notochord post-embryologically?
Notochord breaks down and forms intervertebral disc nucleus. Also initiates the formation of the central nervous system (brain).
Describe the vertebral column
Only In vertebrates, the vertebral column is a series of irregularly shaped elements (cartilage and/or bone) that protect the nerve cord and provide axial support. Land animals rely on it since it's more rigid and resistant to gravity, though fish still retain some notochord elements due to flexibility required underwater.
What are the three general "sections" of the vertebrate body, and what characteristics do they have?
1. Head - Cephalization - usually the location of sensory organs
2. Body - Contains viscera and central support for the appendages. Can also consist of a slender stalk connecting the head (the neck)
3. Tail - Begins at the caudal opening of the digestive tract - the anus. Often lost post-embryologically or after a certain level of maturation. Can be used for defense/swimming/support/etc...
List the eight characteristics vertebrates share with invertebrates
1. Cephalization 2. Complete Digestive Tract
3. Bilateral Symmetry 4. Metamerism (segments with distinct function?) 5. Triploblasty 6. Eucoelomate body Cavity
7. Closed circulatory system 8. Deuterostomy
List the 8 directional terms associated with anatomy and their 4 correlated axes
Proximal/Distal, Ventral/Dorsal, Left/Right, Anterior/Posterior
Proximodistal Axis, Dorsoventral Axis, Left/Right Axis, Anteroposterior Axis
Name the 3 axes commonly used with quadripedal organisms
Cranial/Caudal (Vertical Axis - Usually parallel to the spine)
Dorsal/Ventral Axis (Saggital, or anterior posterior axis - perpendicular to the spine)
Left/Right Lateral Axis
Define the 3 planes of symmetry and which 2 axes run together to create it.
Saggital - Cranial/Caudal intersects with Anterior/Posterior
Frontal (Coronal) - Cranial/Caudal intersects with Left/Right
Transverse (Cross-Section) - Dorsal/Ventral intersects with Left/Right
List the five movements of bilateral symmetry
Flexion, Extension, Abduction, Adduction, Rotation