Vertebrata and fish

Question 1

What advantages do vertebrate have over invertebrates?

Answer 1

• increased complexity
• increased body size
• increased activity
• capturing food and avoiding predators

Question 2

6 shared, derived characterisitcs of vertebrates?

Answer 2

Vertebral column
Braincase enclosing brain
2 or more sets of Hox genes
Neural crest cells
Dorsal, anal and tail fins stiffened by fin rays
Complex, circulatory system

Question 3

What is the vertebral column and what does it do?

Answer 3

Skeletal elements enclose and protect the nerve cord
- replaces the function of the notochord
- enhances rigidity and provides muscle attachment points
- improved food capture and evasion

Question 4

Cranium and head structure and functions?

Answer 4

Associated with pronounced cephalization
- head has brain, sense organs and cranium without jaws
- evolution of cranium allowed exapansion of nerve cord into brain and nervous system
- cranium does not completely encase brain in some vertebrates

Question 5

What are neural crest cells and what do they do?

Answer 5

• develop along neural tube edge in vertebrate embryos
• migrate within embryo, contribute to teeth, skull bones/cartilage and diverse types of neurons

Question 6

What are fins and what do they do?

Answer 6

membrane extensions supported by cartilaginous or bony spines
- provide balance and propulsion during swimming
- lost in tetrapods

Question 7

How does the vertebrate circulatory system function?

Answer 7

• closed circulatory system
• heart with atleast 2 chambers
• O2 transporting hemoglobin in red blood cells; oxygenated via gills or lungs
• kidneys remove waste from blood

Question 8

What is the clade of vertebrates that lacks jaws called? What animals does it comprise? (2)

Answer 8

Cyclostomes
hagfish, lampreys

Question 9

Hagfish characteristics? cranium, vertebrae? anatomy? feeding? defense?

Answer 9

• cartilaginous cranium and reduced vertebrae
• flexible rod of cartilage derived from notochord
• small brain, eyes and mouth
• tooth-like keratin projections that protract and retract to pull in food
• absorb nutrients through skin
• exude fibrous slime for defense which absorbs water and swells rapidly choking predators
• bottom-dwelling scavengers

Question 10

Lamprey characteristics? skeleton and vertebrae? fins? feeding?

Answer 10

• cartilaginous skeleton, more elaborate cranium with gill basket
• rudimentary vertebral elements
• notochord surrounded by cartilaginous segments
• no paired lateral fins; dorsal and tail fins
• suspension-feeding by burying into substrate
• parasitize fish by funnel-like sucking mouth
• rasping tongue with keratin spines

Question 11

What was clade Conodonts and its characteristics?

Answer 11

• earliest vertebrates
• cartilaginous cranium and vertebral column
• jawless but had mineralized skeletal elements in mouth and pharynx
• defensive plates made of dermal bone on their skin

Question 12

What clade makes up jawed fish and what are its shared, derived characteristics? (6)

Answer 12

Clade Gnathostomes
Opposing jaws
2 pairs of lateral appendaged
Mineralization of skeleton
Genome duplication
Enlarged forebrain
Lateral line system

Question 13

What was the structure and purpose of opposing jaws?

Answer 13

• evolved from skeletal supports of pharyngeal slits
• open and close forecefully to capture and process food
• 2 pairs of branchial elements - hinged skeletal rods supporting gill arches - open and close mouth effectively to pump water over gills
• evolution of larger, wider mouths to capture larger prey
• posterior branchial elements for gas exchange (gill slits)

Question 14

What can the 2 pairs of lateral appendages be?

Answer 14

fins or legs

Question 15

What is the significance of genome duplication?

Answer 15

duplication of Hox genes (4 sets)
More specialization and differentiation

Question 16

What is the significance of an enlarged forebrain?

Answer 16

Enhanced smell and vision

Question 17

What does the lateral line system do?

Answer 17

Detects vibrations in water
Lost in terrestrials

Question 18

What is the significance of a mineralized skeleton?

Answer 18

• increased structural support
• protection of internal organs
• ability to support increased size

Question 19

Why did mineralization of the skeleton and evolution of jaws emerge simulataneously?

Answer 19

natural selection favoured mineralization in jaw area enhancing strength and durability
- improved effectiveness of jaws as predatory structures
- mineralization of axial skeleton occurred later for better bodily support and locomotion

Question 20

What are the 2 types of bones in gnathostomes?

Answer 20

Preformed cartilage
Intramembranous ossification

Question 21

How is the endoskeleton derived from preformed cartilage?

Answer 21

Cartilage undergoes ossification with calcium phosphate as embryo develops

Question 22

What is the significance of intramembranous ossofication?

Answer 22

Developed dermal skeletal structures.
- formed external armour in armoured fish
- retained in bony fin rays in fish, facial and pectoral bones and teeth

Question 23

What are the 3 lineages of extant gnathostomes?

Answer 23

Chondrichthyans, lobe-fins, ray-fins

Question 24

Chondrichthyan structure?

Answer 24

-cartilaginous skeletons and endoskeleton
- bony teeth, bony placoid (tooth-shaped scales)
- derived from bony skeletal elements in ancestors

Question 25

How do sharks swim?

Answer 25

- propulsion by tail fin - lift by pectoral fins - streamlined body - swim continuously to maintain buoyancy due to density - no gas-filled swim bladder

Question 26

How do sharks exchange gas?

Answer 26

ram ventilation - swim with mouth open allowing water to pass over gills, facilitating ventilation - may use buccal pumping - force water over gills by opening and closing mouth forcefully

Question 27

Shark anatomy and sensory structures?

Answer 27

Digestive, urinary and reproductive tracts empty through cloaca - acute senses; olfactory receptors, electroreceptors, lateral line system

Question 28

How do sharks reproduce?

Answer 28

copulation males have modified pelvic fins called claspers which deliver sperm to female cloaca eggs are fertilized internally and develop through all 3 methods oviparous - fertilized eggs laid outside body, encased in protective, leathery casing ovoviparous - embryo development in uterus, embryo nourished by egg yolk viviparous - embro development in uterus, nourished through yolk-sac placenta connected to mothers bloodstream

Question 29

What is the Clade of bony fish called and what does it refer to? 3 shared dervived characteristics?

Answer 29

Clade Osteichthyans aquatic bony vertebrates (paraphyletic) - Lungs/lung derivatives - Operculum - Maneuverable fins

Question 30

What is a swim bladder and how did it evolve?

Answer 30

Air sac that maintains neutral buoyancy of fish by adjusting its inflation via gas exchange with blood. Evolved from simple lungs in ancestors - homologous to tetrapod lungs - in primitive ray-fins pneumatic duct connects gut to swim bladder - lost in most ray-fins, resulting in closed swim bladder

Question 31

What is a simple lung and its function?

Answer 31

Dorsal out-pocketing of gut filled with gas - augments gas exchange in gills - gulp air in O2 poor waters

Question 32

What is the operculum and its function?

Answer 32

Plate of dermal bone that covers and protects gill arches and gills - fishes breathe by drawing water over operculum-protected gills - mouth and operculum function as valves in an efficient buccal pump allowing for ventilation even when staitonary

Question 33

What does the fin structure look like in Osteichthyans? What is their function?

Answer 33

- slender, flexible bony rays or spines portruding from the body are covered in skin to form maneuverable fins - pectoral and pelvic girdles support maneuverable fins from bony, basal elements - only the tail fin is directly connected to the vertebral column, rest are supported by muscles - function in propulsion, maneuvering and defense through spines

Question 34

How do bony fish reproduce?

Answer 34

Broadcast spawners and external fertilization - fertilized eggs and young may recieve paternal care - some species exhibit internal fertilization and ovoviparity

Question 35

What are some chacrateristics of bony fish?

Answer 35

- ossified endoskeleton - lateral line system - dermal armour of thin, plate-like bony scales (protection + flexibility)

Question 36

What are the 2 groups of bony fish, their phylogeny and fin structure?

Answer 36

Ray-fins - monophyletic - fins supported by elongated, fleible bony rays connected to basal bony elements Lobe-fins - paraphyletic - fleshy, lobed fins

Question 37

Lobe-fin structure and skeleton?

Answer 37

- fleshy, muscular pectoral and pelvic fins supported by bony elements - lobe-fins are shared, derived trait - single basal skeletal bone and central supporting bones - skeletal elements homologous with tetrapod limb bones

Question 38

3 surviving lineages of lobe-fins?

Answer 38

Coelocanths, lungfish, tetrapods

Question 39

Coelocanth characteristics? Fins? Movement? Gas exchange?

Answer 39

- muscular pectoral anf pelvic fins to swim and walk underwater - lungs and gills - extant genus has vestigial lung

Question 40

Lungfish characteristics? gas exchange? survival?

Answer 40

- gills and lungs - buccal pump system to gulp air from surface by raising and lowering the floor of their mouth cavity - 2 lungs, homologous to tetrapods - burrow into mud in dry conditions