Unit 1 Flashcards
Morphology
Physical appearance
Function
The role a trait/structure has for an organism in nature.
Functional morphology
The actions of a structure and how it works in the organism
Ecomorphology
The role of a trait in the environment. Can change according to life span/life stage/environment/etc.
Evolution
Observing the presence of structures in an organism’s ancestors.
- shows why structures are present
- phylogenetic trees hypothesize evolutionary relationships
Dissent
How anatomical structures came to be (according to a phylogeny)
Extant vs. extinct
Extant - currently exists
Extinct - no longer exists
How long ago did life on Earth begin?
How old is Earth?
4 billion years ago life began.
Earth is 4.6 billion years old.
What are the seven levels of biological classification?
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
What is the classification of Chrodata?
Phylum
What is the classification of Cephalochordata?
Subphylum of phylum Chordata
What is the classification of Urochordata?
Subphylum of phylum Chordata
What is the classification of Vertebrata?
Subphylum of phylum Chordata
What are the major lineages of the phylum Chordata?
Three subphylums: Cephalochordata, Urochordata, and Vertebrata
What is the subphylum of the Phylum Chordata that is most closely related to the true Vertebrates?
Urochordata
What is one characteristic that unites the Chordates?
A notochord.
What are deuterostomes defined as?
The blastopore becomes the anus, and the second opening becomes the mouth.
What domain is being studied?
Eukarya
What is the study of living, extant forms to identify how structures are related to their ancestry?
Comparative vertebrate anatomy.
What are the advantages of comparative anatomy?
- Easy access to specimens
- Can observe functions
- Get to collect whole specimens
- Observe soft tissue
What is a disadvantage of comparative anatomy?
Don’t have the time element (ancestors)
What is the term used to describe similar structures that evolved independently in two organisms to serve the same purpose?
Analogous
What is the term used to describe structures that look the same for two organisms but not because of ancestry?
Homoplasy
What term is used to describe when 2 or more organisms with different evolutionary backgrounds develop the same or similar adaptations?
Convergence
What time period had the early chordates?
Cambrian
What time period had the placoderms?
Silurian
What time period had the chondrichtheys and ostracoderms?
Ordovician
What time period had the gnathostomes and the vertebrates?
Cambrian
What does “Paleozoic” mean?
Age of the fishes
What does “Mesozoic” mean?
Age of the reptiles
What does “Cenozoic” mean?
Age of mammals
What is a skeletal rod which is derived from mesodermal tissue and consists of 3 layers in cross-section?
Notochord
What is the higher level of classification for tunicates?
Urochordata
What is the higher classification for acornworms?
Hemichordata
What is the higher classification for lancelets?
Cephalochordata
What is heterochrony?
Looks at the rate of growth of a structure, the onset and offset, between ancestors and descendants.
What are the two different forms of heterochrony?
Peramorphosis and Paedomorphosis.
What is Peramorphosis?
When the features of adult ancestors are exaggerated or extended in adult descendants.
What are the three ways peramorphosis can occur?
- Hypermorphosis: late offset
- Acceleration: fast rate of growth
- Predisplacement: early onset
What is Paedomorphosis?
Juvenile features are retained in adults.
What are the two forms of paedomorphosis?
- Progenesis: somatic development stops early and sexual development is accelerated.
- Neoteny: somatic development is slowed and sexual development is normal.
What is the function of the notochord?
Prevent the body from collapsing due to its rigidity, allows for lateral flexion and forward motion.
What structure has outer elastic tissue, a middle layer of collagen, and an inner layer of vaculated-fluid-filled cells?
Notochord
What happens to the notochord over evolutionary time?
Over time, it becomes cartilaginous and then ossified.
Where are remnants of the notochord in mammals today?
The nucleus pulposus of the intervertebral disc.
How are pharyngeal slits used?
First used for filter feeding (as a part of the digestive tract), and then evolve to associate gills for gas exchange/respiration.
What are some of the structures that make up the pharyngeal slits?
Pharyngeal arches which separate the pharyngeal slits; brachial plates separated by ectodermal grooves and endodermal pouches; striated muscle; cranial innervation; aortic arch.
In gnathostomes, there are how many paired pouches on the lateral sides of the pharynx? How many in agnathostomes?
8 in gnaths
15 in agnaths
The first pharyngeal arch becomes what in jawed vertebrates?
The mandibular arch
The mandibular arch is made of what two structures?
The palatoquadrate and Meckel’s cartilage.
The second pharyngeal arch becomes what in jawed vertebrates?
The hyoid bone
What is the function of the endostyle?
Iodine metabolism via production of T3 (triiodothyronine) and T4 (thyroxine).
Where is the endostyle found?
At the base of the pharynx.
What structure becomes enlarged at the anterior end and becomes the brain in later species?
DTNC
The DTNC forms the CNS from what type of tissue?
Ectodermal
When the neural plate invaginates, what does it become?
DTNC
What is the fluid called that fills the DTNC?
Neurocoel
This structure acts as an extension of the locomotive apparatus for movement, and includes the notochord and musculature.
Postanal tail
What are the major Agnathostome lineages?
- Myxinoidea (hagfish)
- Petromyzontiformes (lamprey)
- Conodonts (extinct)
- Ostracoderms (extinct)
What are the major lineages of Gnathostomes?
-Placodermi (extinct)
-Acanthodii (extinct)
-Elasmobranchii
-Teleostomi
-
-
What kind of development do Annelida and Arthropoda have?
Protostome
What kind of development do Chrodata, Echinodermata, and Hemichordata have?
Deuterostome
During early embryonic development _____ is observed in deuterstomes at the 32 cell stage, when cells divide form directly on top of the previous set of cells.
Radial cleavage
What happens during spiral cleavage?
The cells rotate
What kind of kidney is it when the mesonephric duct incorporates additional posterior tubules?
Opisthonephros
What kind of kidney is it when a posterior duct forms at the base of the mesonephric kidney ultimately becomes the ureter?
Metanephros
What type of kidney is it when tubules form in the middle and form a connection with the pronephros?
Mesonephros
What kind of kidney is it when the tubules form anteriorly?
Pronephros
What are types of kidneys do we go through in embryological development?
- Pronephros
- Mesonephros
- Metanephros
What hallmark characteristics of the chordates are present in the hemichordates?
- pharyngeal slits
- DTNC
What are the 3 distinguishing characteristics of myxinoidea?
- 1 nostril
- 1 semicircular canal
- Absence of vertebrae in adults, sort of present in larvae
What are two diagnostic features of agnathostomes?
Neural crest and epidermal placodes.
What time period had the Chondrichthyes and the Ostracoderms?
Ordovician
What time period had the Early Chordates, Vertebrates, and the Gnathostomes?
Cambrian
The splanchnocranium derived from the neural crest has 5 pharyngeal arches called the branchial arches. A single arch has 5 structures:
I Pharyngobranchial II Epibranchial III Ceratobranchial IV Hypobranchial V Basibranchial
Myxinoidea - hagfish
Are there vertebrae?
Larvae have skeletal elements, but no vertebrae in adults
Myxinoidea - hagfish
Do they have paired fins?
No
Myxinoidea - hagfish
What kind of kidney do they have in their adult form?
Mesonephric
Petromyzontiformes - Lamprey
What kind of kidney do they have?
Opisthonephric kidney - they are anadromous
Petromyzontiformes - lamprey
What are their distinguishing features?
- 1 nostril
- 2 semicircular canals
- nasohypophyseal duct ends as blind sac
- has signs of cartilaginous vertebral column
Conodonts - extinct lineage of agnaths
What features were discovered about them?
- had myomeres
- had notochord
- had caudal fin rays
- had DTNC
- had big eyes
Ostracoderms - extinct lineage of agnaths
What were their distinguishing features?
- 2 nostrils
- 2 semicircular canals
- nasohypophyseal duct ends as blind sac
Ostracoderms - extinct lineage of agnaths
How were they shaped - what did they look like?
- Dorsal-ventrally flattened
- some had paired appendages
- 1st evidence of true bone, externally
- fused bone plates
- were small
Which of the following Hallmark Characteristics of he Chordates are present in the Hemichordates?
DTNC notochord past anal tail endostyle/thyroid pharyngeal slits
DTNC
pharyngeal slits
Which of the following Hallmark Characteristics of he Chordates are present in the Urochordate adults?
DTNC notochord past anal tail endostyle/thyroid pharyngeal slits
Endostyle/thyroid
Pharyngeal slits
Which group of genes are responsible for dorsal ventral patterning in all animals?
hox or homeobox genes
When change in shape and size occur at a constant and proportional rate
Isometry
A change in shape correlated with a change in size occurring during development
Allometry
Which type of bone is formed from a cartilaginous precursor?
Endochondral bone
A hollow tube which is positioned dorsal to the notochord and is formed from ectodermal tissue
DTNC
Which of the following Hallmark Characteristics of the Chordates are present in the Urochordate larvae?
DTNC notochord past anal tail endostyle/thyroid pharyngeal slits
All five Hallmark Characteristics are present.
*These structures are unique to vertebrates and arise as thickenings from ectoderm, ultimately forming different types of sensory receptors.
*
Which genes are expressed in which regions of the Chordates and Bilateria + Hemichordates + Echinoderms?
Chordates:
- Chordin: Dorsal
- BMP: Ventral
Bilateria + Hemichordates + Echinoderms:
- BMP: Dorsal
- Chordin: Ventral
*Which “rule” suggests chordate evolution proceeded through heterochrony from an echinoderm larval form to modern vertebrates?
*
*From dorsal to ventral, what is the order of pharyngeal bones???
*
When 2 or more structures are similar due to convergence on the same solution
Homoplasy
When 2 or more structures have the same function
Analogy
*What is the sensory structure that is used to help detect vibrations in the water?
*
*What is the term used to describe the tail-type in chondichthyians in which the tail turns upward and the vertebral column extends into the dorsal lobe of the the tail; the tail is asymmetrical?
*
*Which type of bone is formed directly from mesenchyme without any cartilaginous precursor?
*
This type of scale possesses dermal bone, thick layer of dentin, and think layer of enamel.
Cosmoid scale
This type of scale possesses dentin and enamel, but lacks dermal bone.
Placoid scale
This type of scale is composed entirely of lamellar bone.
Teleost scale
This type of scale possesses dermal bone and a thick layer of enamel, lacking dentin.
Ganoid scales
Yellow appearance, mesodermal origin, 70% hydroxyapatite/30% organics + water, also known as cosmine
Dentin
White appearance, epidermal origin, 96% hydroxyapatite/4% organics + water, also known as ganoin.
Enamel
*These cells are unique to vertebrates and give rise to several adult structures after breaking loose of the ectoderm and migrating to various locations in the body, such as melanocytes or odontoblasts.
*
Do petromyzontifomes have vertebrae as adults?
Yes
Do myxinoidea have vertebrae as adults?
No
*What taxon arose in the Late Ordovician time period?
*
*What taxon arose in the Early Cambrian period?
Chordates
*What taxon arose in the Mid-Cambrian period?
*
*What taxon arose in the Early Ordovician time period?
*
*What taxon arose in the Silurian period?
Placoderms
*What taxon arose in the Late Cambrian period?
*
*What “rule” states “ontogeny recapitulates phylogeny”?
*
To which phylum do mammals, birds, reptiles, and fishes belong?
Phylum Chordata
Skeletal rod which is derived from mesodermal tissue and consists of 3 layers in cross-section.
notochord
Which of the following Hallmark Characteristics of the Chordates are present in the Cephalochordates?
DTNC notochord past anal tail endostyle/thyroid pharyngeal slits
pharyngeal slits
notochord
past anal tail
These features are consistent with the Placodermi or the Chondrichthyes?
- Jaw with sharp teeth modified for tearing
- entirely extinct
- reproductive strategy: viviparity
- head covered with fused plates of dermal bone
Placodermi
These features are consistent with the Placodermi or the Chondrichthyes?
- Jay with modified placoid scales as teeth
- extant, with many extinct lineages
- reproductive strategy: viviparity, ovovivparity, oviparity
- head lacking fused scales
Chondrichthyes
Multiple lateral paired openings which pierce or partially pierce the body wall, initially used as part of the filtering/feeding apparatus.
Pharyngeal slits
Structure located posterior to the anus and primarily involved in movement or stability
post anal tail
A glandular groove which forms in the floor of the pharynx and is critical for iodine metabolism.
endostyle
During early embryonic development _______ is observed in deuterostomes at the 32 cell stage, when cells divide and form directly on top of the previous set of cells.
Radial cleavage
What are characteristics of gnathostomes?
- teeth with dentin
- jaw
- true paired appendages
What is the structure that is positioned anterior to the first gill slit in chondrichthyians that is involved in inhalation by drawing water in while the mouth is open?
Spiracle
