6-8: Vertebrate Origin, Jawed Vertebrates, Fish Evolution Flashcards

1
Q

Chordates are spilt into…

A

Cephalochordates, urochordates, vertebrates

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2
Q

Vertebrates are split into…

A

Cyclostomes, gnathostomes

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3
Q

Fundamental structures of chordates

A

Notochord + myomeres, dorsal nerve chord, pharyngeal gills and endostyle

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4
Q

What’s the notochord + myomeres?

A

Rigid rod along body. In vertebrates, the notochord becomes vertebrae. Allow lateral undulations for swimming. Without, would have a slug/leech-like movement

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5
Q

What’s the dorsal nerve chord?

A

Runs along top of back (dorsal). In invertebrates, the nerve chord is ventral. Often a brain attached to anterior end

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6
Q

What are the pharyngeal gill slits and endostyle?

A

Breathe in through mouth, water passes out over gills.
Used in combination with the endostyle for filter feeding in early chordates.
In higher vertebrates, become gill arches and thyroid

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7
Q

Features of cephalochordata

A

Small, filter feeding marine animals
Also called lancelets
Simple morphology
They are the typical chordate, seen in basic diagrams

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8
Q

Features of urochordata

A

Tunicates/sea squirts
Marine invertebrates
Can be colonial, pelagic, can form a mucus ‘house’ around themselves- called a test
Filter feed using siphons
Juvenile has the chordate features, anchors itself and digests brain etc

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9
Q

What are cyclostomes? (agnatha)

A

Jawless vertebrates: lampreys and hagfish

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10
Q

What are gnathostomes?

A

Jawed vertebrates

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11
Q

What is the neural crest in vertebrate development?

A

A migratory multipotent cell population.

It can become parts of te brain, endocrine glands, head/face, teeth and jaws, circulatory system etc

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12
Q

How many whole genome duplication events have vertebrates undergone?

A

2

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13
Q

What genes control body plan layout?

A

Hox genes

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14
Q

Lamprey features

A
Anguilliform (eel-like)
Parasitic freshwater-marine lifecycle
Show semelparity- have a single breeding event
No bones/jaws, just cartilage
Oral suckers with keratinous teeth
Sucking velum apparatus
Vertebrae
Brain, cranium, sensory organs
Single dorsal nasal opening
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15
Q

Lamprey development

A
Larval stage (ammocoetes)
Ammocoetes make burrows and are filter feeders
Blind
No oral suckers
Anatomically similar to cephalochordates
Metamorphosis to adult stage
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16
Q

Lamprey scientific name

A

Petromyzontida

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17
Q

Hagfish scientific name

A

Myxinoidea

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18
Q

Hagfish features

A
Anguilliform
Blind
Deep marine scavenger/predator
Secrete gross gelatinous slime, twist to escape
No bones/jaws, just cartilage
Burrow int carcasses
Rasping keratinous teeth- bite by rasping
Velum and tongue apparatus
Anterior single nasal opening
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19
Q

Hagfish development

A

Don’t know much about them
Eggs hard to grow in lab as they are deep sea creatures
Discovered neural crest in 2007

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20
Q

Gnathostome features

A
Paired pectoral and pelvic fins
Bones and dentine
Hinged jaws
Paired nostrils
Ribs and ventral vertebrae
Internal gill arches
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21
Q

What is taphonomy?

A

The study of fossilisation
Look at current anatomy and how it decays
Decaying organisms lose synapomorphies, and so appear more primitive
Can estimate what features should be present after decay
Allows us to look at fossils and group them

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22
Q

What are ostracoderms?

A

Fossil jawless fish
Means ‘bony skin’
Lots of different types

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23
Q

What are conodonts?

A

Ostracoderms- ‘cone teeth’
Tooth-like elements with dentine
Body with eyes
Muscle blocks, tail fin

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24
Q

What are thelodonts?

A

Ostracoderms- ‘nipple teeth’
Shark-like scales on body
Maybe a bit like sharks?
The evolution of teeth could have started on the body

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25
What are Placoderms?
``` Fossil jawed vertebrates Have simple hinged jaws Don't have proper teeth, just an extension of the jaw Predators with a strong bite Earliest example of live birth ```
26
What is the traditional segmentalism theory of jaw evolution?
Hyoid and mandibular arches are specialised anterior gill arches But little evidence to support
27
What is the specification of upper and lower jaw theory of jaw evolution?
Hox gene expression specifies the arch identity along the body Dlx expression specifies upper and lower jaws
28
Who lost the End Devonian extinction?
Ostracoderms | Placoderms
29
Who survived the End Devonian extinction?
Chondrichthyes Actinopterygii Tetrapods- became us!
30
What are Chondrichthyes?
Cartilaginous fishes
31
What are Chondrichthyes split into?
Elasmobranchii and Holocephali
32
Features of Chondrichthyes
Placoid scales- dermal denticles, homologous with teeth, reduce drag Pelvic claspers- males use them to attach to females to inject sperm Lateral line system- line of sensory cells (neuromasts) across bodies of many fish,. Mechanoreception detects small changes in water pressure Ampullae of Lorenzini- network of jelly filled pores for electroreception
33
What are Elasmobranchii?
Sharks and rays
34
Features of elasmobranchs
``` Usually 5 gill openings Spiracle opening Rigid fins Shed their continually growing teeth Grow around 12 teeth a day 2 clades ```
35
What are elasmobranchii split into?
Selachii (sharks) and Batoidea (rays
36
What are Selachii?
Sharks
37
What are Batoidea?
Rays
38
What are Holocephali?
Rat fish
39
Holocephali features
Pre-pelvic claspers Frontal tentaculum- don't really know what its for Tooth plate- part of the upper jaw, fused to the skul
40
What are Actinopterygii?
Ray-finned fish
41
What are actinopterygii split into?
Chondrostei Holostei Teleostomi
42
What are Chondrostei?
Type of actinopterygii | Include sturgeons, paddlefish, reedfish
43
What are Holostei?
Type of actinopterygii | Include bowfins and gars
44
What are Teleostomi?
Type of actinopterygii | Around 25,000 modern species
45
Anatomy of actinopterygii
``` Bony endoskeleton Fin rays Air filled swim bladder Operculum (flap covering a single gill opening) Overlapping bony scales ```
46
What's the slim bladder for?
Filled with gas to maintain position in the water column
47
What are Sarcopterygii?
Lobe-finned fish
48
What are Sarcopterygii split into?
Actinistia (Coelocanths), Dipnoi, Tetrapods
49
Sarcopterygii anatomy
Fleshy lobed fins | Humerus is the single connection to the supportive girdle
50
How do Osteichthyes maintain buoyancy?
Swim bladder- connected to the gut, or can be entirely internal Lactic acid secretion at a gas gland causes oxygen to be released from the blood Homologous with tetrapod lungs
51
How do Chondrichthyes maintain buoyancy?
Don't have a swim bladder Have a large oily liver (squalene oil) for lift Dynamic lift from pectoral fins and tail
52
Types of breeding (8)
``` Oviparity Ovoviviparity Ovuliparity Viviparity Hermaphroditism Sexual dimorphism Parthenogenesis Sexual parasitism ```
53
Oviparity
Internal fertilisation Female lays eggs that develop externally Eg. mermaids purse from sharks
54
Ovoviviparity
Embryos develop inside the female, egg hatches inside Get nourishment just from the egg Eg. basking sharks, anacondas
55
Ovuliparity
External fertilisation Broadcast spawning- all release egg and sperm into the water Eggs develop externally Eg. Cnidaria, Ctenophora, Echinoderms
56
Viviparity
Embryos develop inside female Nutrients from the adult, no eggs Eg. seahorses, humans, cattle
57
Hermaphroditism
Change sex over time Male to female = protogyny Female to male = protoandry Eg. Indo-Pacific cleaner wrasse. Form harems of one large male and smaller females. If male dies, largest female becomes male within 2 weeks!
58
Sexual dimorphism
Males and females look different Eg. Peacock spiders (jumping spiders). Some debate as to whether sexual dimorphism exists- Wallace (vital energy causing intensified colour), Peckham says yes. Eg. sneaker males that look like females, so can sneak past the guarder male to mate with females
59
Parthenogenesis
Females produce offspring asexually | Seen in sharks and teleosts, and some species of scorpion
60
Sexual parasitism
Deep sea angler fish exhibit extreme dimorphism | Male is tiny, attaches permanently to female like a parasite
61
Teleosts are split into
Acanthomorpha | Non-acanthomorpha
62
Acanthomorpha
Eg. Cod, dories Over 18,000 species (out of 25,000) Very diverse shapes Protrusion feeding
63
Non-Acanthomorpha
Eels, herring, carp, tetras
64
Protrusion feeding
Use premaxilla to estimate distance of protrusion Increased over time Now 21.4% of original distance
65
Swimming forms (4)
Anguilliform eg. eels Carangiform eg. mackerel Thunniform eg. tuna Ostraciiform eg. puffer fish ACTO! Less laterally flexible
66
Anguilliform
Eg. eels | Lots of head movement
67
Carangiform
Eg. mackerel | A fair bit of head movement
68
Thunniform
Eg. tuna | A little bit of head movement
69
Ostraciiform
Eg. puffa fish | Basically no head movement