Ichthyology Final Exam

Lectures 12 - 23: mini quizzes and key information

What is the vicariance hypothesis? What fish
family provides evidence for the vicariance
hypothesis?

• Species distributions are shaped by
  geographic isolation

• The division of the population due to the appearance of a new geographical barrier

• Family Scombridae - Spanish mackerel

What geologic era is known as “the age of fishes”?

Devonian

What is the most diverse marine zoogeographic region? Why is it so diverse?

Indian-West Pacific because of the Coral Triangle being a biodiversity hot spot for many different marine fish and animals

Why is Eastern Atlantic relatively depauperate compared to the Western Atlantic?

Messinian Salinity Crisis ~ 6 MYA: eliminated most fishes

What are two key reasons why freshwater fish have so much more diversity per unit area compared to marine fish?

Productivity:

• Shallower water = more sunlight = rich food web base

Isolation:

• Freshwater is frequently broken up into isolated bodies of water

What is a species flock? How are they formed?

A species flock is a group of closely related species that share a common ancestral species and that are endemic to an isolated region (single lake or island)

Flocks evolve when newly created habitat opens niches which are then colonized by species

What is the most biodiverse freshwater zoogeographic region. What is the most diverse group of fishes in this region?

Neotropical and Characins (tetras)

Name three characteristics found in chordate Conodonts:

• V-shaped myomeres

• Bilobate head

• Cartilaginous skeleton

• Eyes in optic capsules

• Likely a notochord

How did members of Superclass Pteraspidomorphi obtain their food?

Jawless filter feeders

Which group is thought to have given rise to modern lampreys?

Superclass Osterostracomorphi

What are the three overarching abilities that were given to fish as a result of the development of jaws?

• Less reliance on armor = greater flexibility and maneuverability

• Broader range of food sources

What do the fossilized pigment cells found within placoderm fossils suggest about them?

Counter shading and color vision

What group gave rise to tetrapods?

Sarcopterygii

Lancelets live in _______ and feed by _______.

Sediment, filtering diatoms via cilia and mucus

Lancelets are morphologically convergent with _____ larvae of _____.

Ammocete, lamprey

What are the three structures lancets lack that make them distinctly un-fish-like?

• Vertebrae

• Scales

• Genital ducts

• Heart

• Red blood cells

• Hemoglobin

• Gills

Hagfish produce mucus using ______

Slime glands

What do hagfish use mucus for?

• Protect from digestive enzymes when inside a prey animal

• Repulse other scavengers (overcome competition)

• Protect against predation

Hagfish lack _____, which were thought to be secondarily lost due to living in the dark.

Complete eyes

What are two important ecological roles of hagfish?

• Key role in cycling carbon and other nutrients

• Scavengers that eat dead and dying prey

• Removal of carrion falls and bycatch discards off ocean floor

Lamprey are in their larval state for _____ years.

3-10

Non-parasitic adult lamprey lose the ability to _____ and are adults for _____ months.

Feed, 6

Lamprey can breathe and eat at the same time because of what structure?

Velum

How do adult lamprey find suitable spawning sites?

Bile acid produced by larvae

What Infraclass do Coelacanths belong to?

Actinistia

What Infraclass do lungfish belong to?

Dipnomorpha

Coelacanths mature at _____ years and have a gestation of _____ years, which makes them vulnerable to _______.

15, 3, slow growth/maturation and small clutch size

A second species of Coelacanth was found in what year and what country?

1997 and Indonesia

What are the two reasons lungfish were intially thought to be amphibians?

• Heart structure

• External gills on juvenile

________ is the group of lungfish that can aestivate for around _____ months/years.

African lungfish, 7 months to 4 years

_______ is possibly the worlds oldest living vertebrate.

Australian lungfish - Neoceratodus

What are two autapomorphies shared by bichirs?

• Finlets with vertical spine and horizontal rays

• Lobe shaped pectoral fin

• Few, small chromosomes

• Recoil aspiration

• Placed at the base of bony fish phylogeny mostly based pn genetic test

Acipenseriformes have a secondarily derived ______ skeleton.

Cartilaginous

Sturgeons have 5 bony rows of _______.

Scutes

Paddlefish sense their prey by numerous ______ organs.

Ampullary receptors

Why are Gar eggs unique?

They are toxic; deadly to small mammals

Bowfin are unique because they have a single median ______ plate and swim via________.

Gular, undulations of long dorsal fin

Infraclass Elasmobranchii includes ______ and ______.

Division Selachii (sharks) and division Batoidae (skates and rays)

What is the largest order of sharks?

Carcharhiniformes - requiem shark

What is the largest order of skates and rays?

Rajiformes - skates

What are three features that are shared among Elasmobranchs.

• Predatory

• Cartilaginous skeleton, structureless skull

• Teeth not fused to jaw, derived from placoid scales

• Subterminal mouth, protrusible upper jaw

• Fin rays are unsegmented ceratotrichia

• 5-7 gill slits

• Lack lungs and gas bladders (large, low-density livers provide buoyancy)

• Spiral valve intestine for increased surface area

• Internal fertilization

What are two ways sharks differ from rays?

• Gill openings on sides

• Anterior edge of pectoral fin not attached to head

• Anal fin present in galeomorphs

• Small lateral spiracle

What sharks can conserve heat and how?

Lamnid sharks conserve heat generated during muscle contractions

The smallest shark is ___cm, and the largest shark is ___ m.

17cm (dwarf lantern shark), 14m (whale shark)

Are sharks viviparous or oviparous?

• Both!

• 40% of elasmobranchs are oviparious (egg laying)

• Most sharks are placental viviparous

Sharks can sense using electroreception using specialized structures called______.

Ampullae of Lorenzini

¼ of all sharks are threatened due to ________.

Overfishing

What are shark fins marketed for?

Shark-fin soup

Most shark species can only withstand ___% population harvest.

5%

What are the four major cohorts of Teleostei? Which one is the most speciose?

• Elopomorpha - eels and tarpons

• Osteoglossomorpha - mooneyes and bonytounges

• Otocephala - herrings, slickheads, milkfish, carps/minnows, characins, catfish, knifefish

• Euteleosta - everything else (most speciose)

What cohort includes tarpon, bonefish, and eels?

Elopomorpha

Cohort Elopomorpha is set apart by ______.

• Leptocephalus (pointed head) larvae with long larval stage

• Thin, numerous rib-like epipleural intermuscular bones

• Maxilla included in the gape

What are the ancestral characteristics of Cohort Elopomorpha?

Maxilla included in the gape

What groups of fishes are included in Order Elopiformes? What are some distinguishing features of Order Elopiformes?

• Tarpons and Ladyfish

• Gular plate and many branchiostegal rays

• Bony scales containing ganoin

What groups of fishes are included in Order Anguilliformes? What are some distinguishing features of Order Anguilliformes?

• “True” eels and gulphers

• Forward and backward movement

• Much reduced or absent paired fins

• Loss of pelvic girdle

• Modified upper jaw

What order is the most speciose of the Elopomorphs?

Order Anguilliformes

What cohort includes arapaima, “Old World” knifefish, and mormyrids.

Osteoglossomorpha

What continent holds the majority of Cohort Osteoglossomorpha?

Africa

What is a distinguishing feature of Cohort Osteoglossomorpha?

Well developed teeth on the tongue that bite against teeth on the roof of the mouth

What is the special adaptations found in mormyrids?

Highly evolved electrical sense that involves both the production and detection of weak electrical fields

Cohort Otocephala all have a connection between the _____ and the ____.

Inner ear and swim bladder

What are the three superorders in Cohort Otocephala?

• Clupeomorpha

• Alepocephalia

• Ostariophysi

What are some distinguishing features of Order Clupeiformes?

• Gas bladder that extends up into braincase and contact the inner ear; also has extensions to the lateral line canal

• Sharp bony scutes

• Modified joint at posterior angle of the jaw

• Caudal skeleton reduced in bone complexity

The Ostariophysi are set apart by _____ and _____.

• Weberian apparatus (series of bones that connect the gas bladder with the inner ear)

• Alarm response (alarm substance and reaction)

Order Cypriniforms includes what four groups of fishes?

Suckers, carp, danio, and minnows

What are the two continents Cypriniformes are not found on?

Australia and South America

What are some distinguishing features of Order Cypriniformes?

• Development of pharyngeal dentition

• First teleosts with highly protrusible upper jaw

• First fish where maxilla is excluded from the gape

What three groups of fishes make up order Characiformes?

• Citharinids

• Tetras

• Charcins

What are some distinguishing features of Order Characiformes?

• Adipose fin

• Well-armed mouths

• Cteniod scales

• Replacement dentition

What continent are Characiformes most abundant in?

South America

What group of fishes make up order Siluriformes?

Catfish

What are some distinguishing features of Order Siluriformes?

• Fusion, reduction, or loss of a number of skull bones

• Teeth on roof of mouth

• Adipose fin

• Unsegmented, spine-like ray at front of both the dorsal and pectoral fins that is covered by a toxin

• Lack of scales, presence of bony plates or tubercles

• Small eyes

• Barbels (chemosensory and tactile functions)

What freshwater fish has the largest east to west range?

Northern Pike

What is the largest family of freshwater fish?

Cyprinidae

What continent are Siluriformes most abundant/diverse?

South America

What group of fishes make up order Gymnotiformes?

Knifefish

What continent are Gymnotiformes restricted to?

South and Central America

What are some distinguishing features of Order Gymnotiformes?

• Produce/detect weak electric impulse

• Elongate, compressiform body (long anal fin; no dorsal or caudal)

• Small eyes

What are the three distinguishing features of Cohort Euteleosta?

• Similarities embryonic development patterns of some of the bones

• Presence of an outgrowth on the stegural bone

• Presence of caudal median cartilages

Order Salmoniformes contains one family and three subfamilies. What are the three families and what is the outgroup family?

• Salmoninae

• Coregoninae - outgroup

• Thymallinae

What is anadromy?

Fish born in freshwater that migrate to saltwater to grow, then return to freshwater to spawn

What is oviparous?

Mother releases eggs that then rely on yolk for nutrition

What is viviparous?

Young develop inside the mother and the mother provides nutrition via a placental connection (skip larval stage)

What is ovoviviparous?

Young develop inside mother but depend on the yolk

What is sequential hermaphrodites?

Function separately as males and females at different points

What is simultaneous hermaphrodites?

Release eggs and sperm during the same spawning

What is protogyny and how is it advantageous?

• Female to male

• Female at smaller sizes and then change to male when larger to maximize mating ability

What is protandry and how is it advantageous?

• Male to female

• Small males produce many sperm; large female maximizes egg production

What is the evolutionary reason why anadromy originated in Salmon? What group of salmon are anadromous?

• To protect young from predators (safe site hypothesis)

• Pacific salmon

What are the key derived characteristics of clade Acanthomorpha?

• Paired jointed dermal fin rays fuse into a single, unsegmented structure

• Strengthening of vertebral accessories allowed better muscle attachment

• Allowed shift from slower sinusoidal motion to rapid oscillation of the tail

• Pharyngeal teeth diversified; maxilla no longer tooth bearing but aids premaxillae in protrusion

What are the three groups of fishes in order Esociformes? What is the largest fish in this order?

• Pike, pickerel, mudminnow

• Muskellenge

What are the distinguishing features of Order Esociformes?

• Maxillary bone included in gape, but toothless

• Median fins located far back on body

What three groups in included in order Osmeriformes? What habitats do they occupy?

Smelts, Ayu, and Icefish

Shallow water marine and freshwater environments

Order Stomiiformes mainly live in the _______, and have _______ and _____ that help them locate and capture prey.

Deep sea, photo pores, large mouths

Which is ancestral and which is derived?

Maxilla excluded from the gape vs. maxilla included in the gape

Ancestral: maxilla included

Derived: maxilla excluded

Which is ancestral and which is derived?

Cycloid scales vs. ctenoid scales

Ancestral: cycloid scales

Derived: cteniod scales

Which is ancestral and which is derived?
True spine fin ray vs. jointed fin rays

Ancestral: jointed fin rays

Derived: true spine fin ray

Which is ancestral and which is derived?

Pectoral fins located laterally vs. pectoral fins located ventrally

Ancestral: pectoral fins located ventrally

Derived: pectoral fins located laterally

Which is ancestral and which is derived?

Pelvic fins located posteriorly vs. pelvic fins located anteriorly

Ancestral: pelvic fins located posteriorly

Derived: pelvic fins located anteriorly

Which is ancestral and which is derived?

Dorsal fin + adipose fin vs. 2 true dorsal fins

Ancestral: dorsal fin + adipose fin

Derived: 2 true dorsal fins