Vertebrate Zoology Test #2

How many species are within Osteichthyes?

>34,000 extant species

What are the 2 main groups of Osteichthyans?

Sarcopterygii & Actinopterygii

Sarcopterygii

Lobe-finned fishes & tetrapods

Actinopterygii

Ray-finned fishes

What are the synapomorphies of Osteichtyans?

• gas containing lung

• branchiostegal rays form the gill-chamber floor

• fin rays with lepidotrichia

• multiple dermal bones in the head (some frequently bearing teeth)

What are the basal groups of Actinopterygii?

Polypteriformes, Acipenseriformes, Lepisosteiformes, and Amiiformes

What is the crown group of Actinopterygii?

Teleostei

Polypteriformes

Diphycercal/modified diphycercal caudal fin.

Acipenseriformes

Heterocercal (unequal-lobed) caudal fin

Lepisosteiformes & Amiiformes

Abbreviated heterocercal caudal fin

Teleostei

Homocercal (equal-lobed) caudal fin

Diphycercal

Primitive and undifferentiated; vertebrae extend to tip of tail symmetrically. (occurs in lampreys, hagfish, & larvae of advance teleosts)

Modified Diphycercal

Vertebrae extend symmetrically to the tip of an expanded tail (convergently evolved in coelacanth, lungfish, ratfish & many eel-like fishes)

Heterocercal

(Unequal-lobed); vertebrae extend into upper lobe (modern sharks & primitive bony fishes like sturgeon)

Abbreviated heterocercal

An intermediate between heterocercal & homocercal

Homocercal

(Equal-lobed); exists in most teleosts; expresses asymmetry internally but symmetry externally

Polypteriformes

Bichirs & Ropefishes

Bichirs & Ropefishes

• 2 extant genera, 12 spp.

  • African freshwater (Nile)

  • Ganoine-covered thick, rhomboid-shaped scales

• Diagnostic character is the series of dorsal finlets

• Fleshy pectoral fins

• Obligate air breathers with lungs

Acipenseriformes

Sturgeons & Paddlefishes

Sturgeons & Paddlefishes

• 2 extant families, 28 spp

• Marine and freshwater

• Live 50-60 years

• Threatened, partially due to caviar

  • Beluga sturgeon caviar ~$5,000 / kg

• Inferior mouth

• Skeleton largely cartilagenous

• Electroreceptiv

Lepisosteiformes

Gars

Gars

• 2 genera, 7 spp.

• Freshwater of North and Central America/Cuba

• Use gas bladder as lungs

• Ganoid scales

• Circumorbitals have teeth

• Spawning aggregations with multiple partners

• Eggs are toxic

Amiiformes

Bowfin

Bowfin

• 1 family with historical 1 species

  • Recent phylogenetic work has split into 2 species

• Weed-filled lake and slow-flowing rivers of North America

• ~ 1 m in length and eats almost anything

• Undulates large dorsal fin to swim

• Males build and protect nests during breeding season

• Not to be confused with the invasive snakehead

  • Look superficially similar

What are the synapomorphies of Teleostei (Bony Fishes)?

• homocercal tail

• thinner scales than gars & polypterids

• pharyngeal jaws

• pelagic eggs

What are the basal groups of Teleostei?

Elopomorpha, Osteoglossomorpha, Otocephala

Elopomorphs

Tarpons & Eels

Tarpons & Eels

• 4 orders & 27 families

• Mostly marine

• Most basal teleost group

• All possess leptocephalus: unique larval stage

• Moray eels: Unique pharyngeal jaws

Osteoglossomorphs

Bony Tongues

Bony Tongues

• possess a special tongue and slicing surface (parasphenoid)

• live in freshwater

• Include: Arapaima & Mormyrids (Elephant Fish)

Clupeomorphs

Herrings, shads, sardines, anchovies

Why are clupeomorphs important?

They are a critical component of the marine food web

Cypriniformes

Minnows, suckers, & loaches

Minnows, suckers, & loaches

• Most are freshwater native to North America, Europe, Asia, and Africa

• LACK oral teeth

• Evolved the kinethmoid

What feature did cypriniformes evolve?

Kinethmoid

What was the kinethmoid used for?

Allows premaxilla to project forward (used in suction feeding)

Characiformes

Tetras & pirahnas

Tetras & pirahnas

• Freshwater, dominant in South America, also native to Africa

• Large variation in sizes and diets

• Noteworthy teeth

• Popular in the aquarium trade

Siluriformes

Catfishes

Catfishes

• Scaleless

• Possess sensory barbels

• Single large spines on dorsal and pectoral fins

  • Usually venomous

How many species do Euteleostei account for?

~20,000

Argentiniformes

Slickheads & barreleyes

Esociformes

Pikes & mudminnows

Pikes & mudminnows

• Ambush predators

• Cryptically colored, use camouflage to conceal

• Freshwater, circumpolar

Salmoniformes

Salmon & Trout

Salmon & Trout

• Native to Northern Hemisphere (introduced to many parts of the world)

• Many anadromous (adult lives at sea, migrate to freshwater to spawn)

• Adipose fin

• Commercially important

  • Salmon roe (eggs) considered a delicacy

What are the orders that can be found in the deep-sea?

Stomiiformes, Myctophiformes, Lampriformes, & Zeiformes

What are some defense mechanisms of the deep-sea fishes?

Counter illumination, smoke screen

What are some offense mechanisms of the deep-sea fishes?

Hunting & lures

What are some ways deep-sea fishes communicate?

Sexual selection & species recognition

Stomiiformes

Dragonfishes & their allies

Dragonfishes & their allies

• Open-ocean deep sea

• Contain the most abundant vertebrates on the planet (bristlemouths; trillions/quadrillions of individuals)

• Bioluminescent 

• Often have chin barbels used for luring prey

• Exceptional camouflage

What are Ctenosquamata?

Include Myctophiformes & Acanthomorphs

Amount of species in Ctenosquamata

Around >20,000 species

Myctophiformes

Lanternfishes and their allies

Lanternfishes and their allies

• Deep sea, worldwide

• Second most abundant group of vertebrates

• Bioluminescent 

• Migrate up and down in the water column twice daily (for food in surface waters)

• Many have sexually dimorphic light organs (different morphology between males and females)

What does Acanthopterygii mean?

Spiny-rayed

What are some synapomorphies of Acanthomorphs?

• Stiff, bony fin spines in the dorsal, anal, and pelvic fins

• Maxilla lacks teeth and supports the premaxilla during jaw projection

• Pectoral fin is on the side of the body

• Premaxilla has elongated ascending process

  • Allows for greater projection of the oral jaws

• Rapid diversification in the late Cretaceous

  • Linked to availability of many new marine habitats, including reefs formed by stony corals similar to those of today

Gadiformes

Cod, haddock, hakes

Cod, haddock, & hakes

• Almost all are marine

• Historically considered some of the most important wild-caught commercial fishes

  • Include deep sea and near shore

• One freshwater species, the Burbot (Lota lota)

  • Many northern ice-fishing tournaments for it

Lampriformes

Opah and oarfishes

Opah and oarfishes

• Iconic marine pelagic fishes

• Usually deep water

• All large but vary in body shape

• Unified by color and jaw protrusion

Oviparous

mostly lay eggs (buried, pelagic, in nests, attached to something)

Freshwater Egg-Laying Fishes

Generally lay a small number of demersal eggs

Marine Egg-Laying Fishes

Generally lay a large number of small buoyant eggs

Viviparous

Give live birth

Parthenogenetic

Population is entirely female and can reproduce/have young from unfertilized eggs

Gonochoristic

Stay as male or female throughout life

Hermaphroditic

Individuals have functional ovaries and testes, generally at different stages of life

Protandrous

Male organs before female

Protogynous

Female organs before male

Simultaneous

Male/female organs at the same time

What does the Sarcopterygii group consist of?

Lobe-finned fishes & tetrapods

What are the 3 main groups of Sarcopterygii?

Actinistia, Dipnomorpha, Tetrapodomorpha

What is the †Tiktaalik?

The †Tiktaalik is of the most well-known extinct transitory species.

What were the challenges of living on land?

• Gravity

• Changes to the Axial Skeleton

• Changes to the Appendicular Skeleton

• Locomotion

• Eating

• Breathing

• Pumping Blood

• Sensory Systems

• Vision

• Hearing/Equilibrium

• Olfaction

• Water Conservation

What did the axial skeleton become the primary source of?

Support and locomotion

The reduction/loss of this allowed for flexibility in neck and head movements in tetrapods?

Supracleithrum

What is the zygapophyses and its function?

Interlocking vertebrae; allows the vertebral column to transfer weight of the body to the limbs

Axial muscles became highly differentiated (compared to fish) with 2 new roles. What were they?

1. Postural support of the axial skeleton

2. Ventilation of the lungs

Differences of changes to the pectoral girdle in tetrapods

Not attached to the skull, now mainly supports the body (not connected to the vertebral column)

Differences of changes to the pectoral girdle in fishes

Attached to the skull and associated with movement of gill arches, lower jaw, and small muscle masses of the pectoral fin

Differences of changes of the pelvic girdle in fishes

Not connected to the vertebral column, just anchors pelvic fins in the body wall

Differences of changes of the pelvic girdle in tetrapods

Now connected to the vertebral column by muscles and connective tissue

What is the importance of the vertebral column?

• supports body weight

• provides a stable base for locomotion on land

• distributes a upper body weight

• includes the ilium, ischium, and pubis (parts of the pelvic bone region)

What are the 3 regions of limbs in the appendicular skeleton?

Stylopodium, Zeugopodium, Autopodium

Stylopodium

(humerus or femur)

Zeugopodium

(radius/ulna or tibia/fibula)

Autopodium

(carpals, metacarpals, phalanges or tarsals, metatarsals, phalanges)

Locomotion in fishes

• fins and sides push back against the water

Locomotion in terrestrial vertebrates

• use legs/feet to transmit backward force onto substrate

• “early” terrestrial vertebrates have a more wave-like motion (called a walking-trot)

• diversity of movement and locomotion exceeds that of fishes

Where can you find the depressor mandibulae?

Runs from the skull to the back of lower jaw

Where can you find the sphincter colli?

Surrounds neck, aids in swallowing

How did paleozoic tetrapods catch their food/prey?

Likely caught and swallowed prey whole (similar to an alligator)

How is the tongue used in terrestrial feeding?

Believed to be a key innovation in terrestrial feeding

• can move food in the mouth and transport to pharynx

• can be sticky and be projected to capture prey

What is the importance of salivary glands?

Only present in tetrapods; gland secretions lubricate food and the enzymes break down food

Circulation in fishes

Single circulation: oxygenated blood from the gills flows straight to the body without returning to the heart

Circulation in tetrapods

Double circulation: pulmonary circuit supplies the lungs with deoxygenated blood and the systemic circuit supplies body with oxygenated blood

• blood is pumped twice to help maintain pressure & reach organs faster

Vision of fishes

Lens is spherical and moves forward/backward in the eye to focus

• most are unable to contract of dilate their iris to regulate light entering

Vision of tetrapods

Lens is thinner and elliptical

• focus is adjusted by muscular contractions that change shape of lens

• muscular iris changes size to adjust to the amount of light entering the eye