Marine Biology Quiz on Elasmobranchii

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Questions and Answers

What exemplifies a derived character state in mammals?

Ability to breathe air

Presence of hair

Absence of hair in whales and dolphins (correct)

Lactation

What defines a sister group in evolutionary biology?

Two clades resulting from the splitting of a single lineage (correct)

A specific adaptation seen in a single species

A group of organisms that are the same age but differ in habitat

Organisms that share a common predator

Which term refers to an organism that thrives in very specific situations?

Generalist

Specialist (correct)

Pelagic

Benthic

What does the term 'benthic' refer to in marine biology?

Species with an affinity for the substrate or bottom Signup and view all the answers

How does global diversity of marine fish vary across latitudes?

More species at low latitudes near the equator Signup and view all the answers

What is the primary mode of respiration for slow-moving, benthic sharks?

Active pumping through the mouth Signup and view all the answers

Which type of teeth are adapted for crushing mollusks?

Rounded and flat Signup and view all the answers

What is a characteristic feature of the ampullae of Lorenzini in sharks?

Detect electric fields Signup and view all the answers

Which feature of elasmobranchii is shared by all members?

Skeleton is cartilaginous Signup and view all the answers

How are placoid scales advantageous for sharks?

Reduce drag while swimming Signup and view all the answers

What unique reproductive feature do male sharks possess?

Presence of claspers Signup and view all the answers

What is the typical feeding behavior of chimera, a type of elasmobranchii?

Scavenging or invertivory Signup and view all the answers

Which structure in sharks is modified from gill slits in some species?

Spiracle Signup and view all the answers

What factors contribute to the faster accumulation of species at high latitudes?

Stable conditions and less competition Signup and view all the answers

Which freshwater river system is NOT mentioned as a major concentration area for species diversity?

Nile River Signup and view all the answers

What feeding strategy do Hagfishes utilize?

Anchoring teeth into flesh and using a knot to pry off flesh Signup and view all the answers

What principle explains why some species can be excluded from a niche?

Competitive exclusion principle Signup and view all the answers

Which structure is characteristic of all Agnatha?

Rudimentary chondrocranium Signup and view all the answers

What mechanism do Lampreys use to feed on their prey?

Creating a wound with their rasping tongue Signup and view all the answers

Which feature is NOT associated with Chondrichthyes?

Swim bladders for buoyancy Signup and view all the answers

How do coral reefs primarily affect fish populations?

By offering complex structures for shelter and food Signup and view all the answers

What is the main reason for the low number of species found near the poles?

Unstable environmental conditions Signup and view all the answers

Which of the following characteristics is NOT found in all Agnatha?

Presence of scales Signup and view all the answers

What characteristic distinguishes rays from skates?

Rays have kite-shaped bodies. Signup and view all the answers

Which of the following features is present in both lungfishes and coelacanths?

A vascularized swim bladder. Signup and view all the answers

What adaptation do lungfishes exhibit to survive in dry conditions?

Aestivation. Signup and view all the answers

What function do the barbels serve in sturgeons?

Assist in filter feeding. Signup and view all the answers

Which characteristic is NOT associated with acipenseriformes?

Strongly ossified skeletons. Signup and view all the answers

What type of scales do extant lungfishes possess?

Cycloid scales. Signup and view all the answers

What is the primary benefit of cycloid scales found in eels?

Flexibility for movement. Signup and view all the answers

How do gars primarily breathe when underwater?

Gulping air from the surface. Signup and view all the answers

What evolutionary significance is attributed to the diversity in scale types among fish?

Niche specialization in different habitats. Signup and view all the answers

What is a unique feature of the Bowfins?

Vascularized swim bladder that acts as a lung. Signup and view all the answers

What distinguishes the embryonic development of eels from that of other fish?

Eels lose and then re-evolve their scales. Signup and view all the answers

Which of the following groups is characterized by the presence of a vestigial lung?

Lungfishes. Signup and view all the answers

What characteristic helps identify reedfishes among other fish?

External gills during juvenile stages. Signup and view all the answers

Which group of fish is known for lacking teeth on their jaws?

Cypriniformes Signup and view all the answers

What function does the Weberian apparatus serve in Ostariophysi fish?

It amplifies sound waves. Signup and view all the answers

Which of the following adaptations is not associated with cave-adapted fish?

Increase in body size Signup and view all the answers

How do anglerfishes attract their prey?

Mimicking invertebrates with lures. Signup and view all the answers

Which type of swimming involves undulating the entire body and caudal fin?

Anguilliform swimming Signup and view all the answers

What unique feature do Characiformes fish possess that aids in identification?

Adipose fin Signup and view all the answers

Which swim bladder adaptation allows some fish species to breathe air?

Modified stomach Signup and view all the answers

Which fish family is known for its members that often exhibit complex behaviors, such as farming algae?

Pomacentridae Signup and view all the answers

What type of swimming mode is characterized by the use of flexible pectoral fins for propulsion?

Labriform swimming Signup and view all the answers

Which type of scale is described as having a flexible and comb-like edge that reduces drag?

Ctenoid scales Signup and view all the answers

What is a key feature of the Siluriformes group of fish?

Absence of scales and production of mucus Signup and view all the answers

Which fin structure allows fish to remain buoyant and is often modified in various species?

Swim bladder Signup and view all the answers

What distinctive feature do Gobiiformes fish lack that affects their swimming behavior?

Swim bladder Signup and view all the answers

Study Notes

Character States

The original condition of a character is called the "primitive character state"
A character whose state has changed from the primitive state is called a "derived character state"
For example, the presence of hair is the primitive character state for all mammals. The absence of hair is a derived character state for one subclade - whales.

Clades and Taxa

Clades are a group of organisms that share a common ancestor.
A sister group is when two clades diverge from a single lineage and are the same age, but the two clades are not necessarily the same age.
Taxa is a term for any group of organisms:
- Species
- Genus
- Family

Terms

Adaptation - a specialized feature that helps an organism survive in its environment
Specialist - an organism that thrives only in very specific environments
Generalist - an organism that can survive and thrive in a variety of environments
Benthic - organisms that live on the substrate or bottom
Pelagic - organisms that live in the open water column

Global Diversity of Marine Fish

More species at low latitudes (near the equator)
- Stable conditions with no seasonality
- More food available due to warm waters and high productivity
- More space for organisms to live and specialize
Species accumulate faster at high latitudes (near poles)
- Unstable conditions with seasonality
- Fewer species due to difficult living conditions
- Competitive exclusion principle: dominant species may restrict the diversity of other species in an area
Coastal areas can be particularly diverse
- Coral reefs provide shelter from predators and are a rich source of food

Global Diversity of Freshwater Fish

Mostly concentrated near the equator focusing on large landmasses with large, warm river systems
- Amazon and La Plata Rivers (South America)
- Congo River (Africa)
- Mekong and Yangtze Rivers (Asia)
- Mississippi River (North America)

Agnatha: Jawless Fishes

Primitive vertebrates that originated in the Cambrian period
Myxiniformes (Hagfishes)
- Vestigial eye
- 4 pairs of sensory tentacles
- Mouth with rasping tongue and keratin teeth
- Mucus gland pores
- 12 external gill slits (paired)
- Slime defense mechanism releases mucin vesicles and skeins of fibrous thread
Petromyzontiformes (Lampreys)
- Eye
- Oral disk with keratin teeth and rasping tongue
- 7 external gill slits (paired)
- Anterior and posterior dorsal fins
- Caudal fin

Chondrichthyes: Cartilaginous Fishes

Consist of ratfish/chimeras, rays, and sharks
Maintain buoyancy with a large oil-filled liver and a heterocercal caudal fin.
Gill openings are independent and physically separate but connected to the esophagus, making them more efficient than pouched gills.
Respiration modes:
- Slow-moving, benthic sharks actively pump water across gills with their mouths
- Spiracle pulls water in and across gills
- Ram ventilation: forward movement passively forces water across the gills
Placoid Scales:
- Present in all species
- Dermal denticles made of dentine and enameloid
- Lightweight, highly protective and reduce drag
Teeth:
- Made of calcium phosphate
- Smooth or serrated
- Replaced throughout life
Ampullae of Lorenzini:
- Electroreceptors that detect electric fields
- Gel-filled pores throughout the body connected to sensory cells
Synapomorphies:
- Cartilaginous skeleton
- Chondrocranium lacks sutures
- Unsegmented soft fin rays
- Teeth not fused to jaws
- Males have claspers for internal fertilization
Chimeroidea (Ratfish/Chimeras:
- Gill cover over 4 gill slits
- Live at depths from 80-2600m
- Scavengers or invertivores
- Upper jaw fused to the chondrocranium
- Males have cephalic claspers
Elasmobranchii:
- Includes Selachii (sharks) and Batoidea (rays and skates)
- Oldest fossil teeth from 418 Mya

Selachii: Sharks

Pelvic fins usually not anchored to the skeleton by the pelvic girdle.
Soft fin rays unsegmented

Batoidea: Skates and Rays

Anatomy: Skates vs Rays
- Rays are live-bearing (viviporous)
- Skates are egg-laying (oviparous)
- Skates have a prominent dorsal fin
- Rays only have a very reduced dorsal fin
- Rays are kite-shaped with ship-like tails
- Skates have fleshy tails
Skeletal Anatomy
- Skeleton is cartilaginous
- Pelvic girdle is fused to the vertebral column, which is a derived feature for Chondrichthyes
- Scapular girdle is present

Sarcopterygii: Lobe-finned Fishes

Consist of Dipnoi (lungfish), Actinistia (coelacanths) and Polypteriformes (reedfish)
Dipnoi (Lungfishes)
- Cosmoid scales (extinct)
- Cycloid scales (extant)
- Distribution of extant species is due to the breakup of the supercontinent Gondwana.
- Burrowing mechanism to survive during dry periods
- Aestivation: A period dormancy during drought periods
Lungfishes can survive up to 5 years during aestivation
Cranial Anatomy:
- Ceratohyal (floor of mouth)
- Clavicle (part of pectoral girdle)
- Cranial rib (an accessory structure associated with their lung) are involved in breathing and feeding
Scales:
- Cosmoid scales (extinct lungfishes)
  - Benefit: durable and provide defense against predators
  - Drawback: poor flexibility
- Cycloid scales (extant lungfishes)
  - Benefit: flexibility
  - Drawback: Limited defense against predators
Actinistia (Coelacanths):
- Vestigial lung derived from the swim bladder
- Filled with fat, rather than air, and is likely an adaption for buoyancy at great depths
- Cosmoid scales: likely derived from the fusion of placoid scales
Polypteriformes (Reedfishes): ~360 Mya
- Juveniles have external gills, resorbed over time
- Respire using lungs, but cannot extract sufficient oxygen from water
- Must periodically surface and gulp air
- Spiracular breathing:
  - Respire through two spiracles on the top of the head
  - Air can pass through spiracles into the mouth
  - If habitat is desiccating, they can make short over-land excursions

Acipenseriformes: Sturgeons and Paddlefishes

Acipenseridae (Sturgeons): ~350 Mya
- 28 species
- Lack scales, possess five lateral rows of bony plates called scutes
- Four barbels (sensory organs in front of mouth)
- Lack teeth
- Skeleton is largely made of cartilage; many bones do not fully ossify
- Commercially harvested for their eggs
Polyodontidae (Paddlefish): ~350 Mya
- 8 species; only 2 extant
- Rostrum (paddle) has 2 functions:
  - Provide lift and stability while filter-feeding
  - Counteract the drag created by the lower jaw that drops below the body
- Lack teeth
- Lack scales
- Ampullae of Lorenzini present

Amiiformes (Bowfins): ~250 Mya

Only 2 species
Very old lineage
Vascularized swim bladder can function as a lung
Protruding tube-like nostrils
Single-layered cycloid scales

Lepisosteiformes (Gars): ~250 Mya

7 extant species
Vascularized swim bladder can function as a lung (similar to Bowfins)
Ganoid scales:
- Rhomboid shape
- 3 layers
- Inner bony plate
- Middle layer of osteodentin
- Outer layer of ganoine
- Largely non-overlapping
- Inflexible and tough
- Benefit: durable and defense against predators
- Drawback: poor flexibility

Actinopterygii: Ray-finned Fishes

Elopiformes (Tarpon):
- 2 species
- Cycloid scales
- Can live in marine and brackish water
- Obligate air breathers: need to have access to the surface
- Likely a unique origin from that in lungfish, reedfish, sturgeons, paddlefish, bowfins, and gars
Anguilliformes (eels):
- True eels
- Scales:
  - Freshwater: small, soft, cycloid scales embedded in their epidermis
  - Marine: lack scales, produce mucus for protection
- Freshwater eels are derived from marine ancestors
  - Lacking scales is viable in marine environments, but not freshwater
- Fins
  - Freshwater: pectoral fins and continuous dorsal, caudal, and anal fins
  - Marine: continuous dorsal, caudal, and anal fins### Osteoglossiformes
“Bony Tongues,” about 245 species
Mostly freshwater
Cycloid scales, most teeth on tongue and roof of mouth

Ostariophysi

More than 11,000 species, all freshwater except Antarctica
Weberian apparatus:
- Minute bones connecting inner ear to swim bladder
- Amplify sound waves by resonating through swim bladder
- Provides enhanced ability to sense vibrations and hear

Cypriniformes

About 4,500 species, cycloid scales
Lack teeth on jaws, lack stomachs, many have barbels (whiskers)

Characiformes

About 2,200 species, well-developed teeth
Adipose fin: tiny fin by caudal fin, distinct character

Gymnotiformes

About 240 species
Lack pelvic and dorsal fins, possess electric organs
Electric organs produce weak electric fields for navigation
Electric eels can stun prey

Siluriformes

More than 3,800 species, majority freshwater
Adipose fin present
Usually negatively buoyant, reduced swim bladder, large bony skull
Lack scales, produce mucus; some have dermal plates
“Armored” have dermal plates or plates derived from vertebral processes
Sound production by flicking pectoral fins
Barbels (whiskers) up to 4 pairs: nasal, maxilla, and 2 pair on dentary
Some breathe air:
- Gulp air into modified swim bladder
- Diffuse air through modified gill arches
- Gulp air into the modified stomach/digestive tract

Esociformes

About 10 species
Esocidae (pikes):
- 7 species
- North America, Western Europe, Siberia
- Sportfish and top predators
Umbridae (mud minnows):
- 3 species
- Mississippi River Basin and eastern US
- Live in stagnant, low-oxygen waters (marshes, ditches, swamps)

Salmoniformes

Food and sport fish, adipose fin present

Percopsiformes

Chologaster: swamp fish live near the surface
Forbesichthys: spring cavefish live in intermittent surface
Typhlichthys: southern cavefish live in sub-surface
Cave adaptations:
- De-pigmentation: loss of selection for visual signaling, colors are expensive to make
- Eye-loss: expensive structures, require vitamins, limited utility in dark
- Elaboration of the lateral line system: mechanosensory (vibrations) and chemosensory (smell) function
- Flattening of head: possible increase in mouth size and sensory receptor surface area

Acanthomorpha

Hollow, unsegmented spines along anterior dorsal and anal fin: can be extended for defense, retracted to reduce drag
Well-developed snout cartilage allows for upper jaw protrusion
Mostly ctenoid scales: outer bony layer, inner fibrous collagen layer with small spines
- Highly flexible for mobility
- Comb-like edge creates turbulence that reduces drag
- Less protection than placoid, cosmoid, or ganoid scales

Holocentriformes

Nocturnal, marine, large eyes
Reddish color provides camouflage in dim light

Batrachoidiformes

Marine, toadfish

Gobiiformes

90% marine, small burrowing species
Lack swim bladder, actively swim to prevent sinking

Scombriformes

Marine, mostly pelagic active swimmers
Fastest swimmers, large predators

Syngnathiformes

Marine, mimic seaweed and coral
Males become pregnant and carry young
Loss of fins: pelvic, sometimes caudal fin
Seahorses have prehensile tails for grasping, slow swimmers

Synbranchiformes

Freshwater, labyrinth organ:
- Vascularized area within branchial arch (gill arch)
- Diffuses inhaled oxygen into blood
- Survive on land if moist

Carangiformes

Mostly large, laterally compressed, silvery fishes
Remoras have specialized dorsal fin that forms a suction cup
- Attached to sharks, whales, turtles, tuna, swordfish
- Commensalism: attachment to host for travel

Pleuronectiformes

Mostly marine, exhibit eye migration during development
Ovalentaria: produce adhesive eggs

Pomacentridae

Farm plots of algae
Longfin Damselfish has a mutualistic relationship with Mysidium integrum
Clownfish have mutualistic relationships with anemones

Polycentridae

Leaf fishes, mimic dead leaves, ambush predator

Cichlidae

About 1,700 species, East African Great Lakes, significant paradox
Distributed throughout Africa, Americas, India, and Madagascar
Freshwater

Perciformes

Triglidae (sea robins):
- Marine, possess sensory organs on pectoral fins
- Used to sift through substrate for food
Percide (perches and darters):
- Large-bodied predators: walleye and perches (sport and food fish)
- Dramatic transition to small bodies: darters
- Darters lack swim bladders, strictly benthic
Centrarchidae (sunfishes and black basses)

Labriformes

Wrasses (more than 400 species) and parrotfishes (about 90 species)
Wrasses and parrotfishes associate with coral reefs
Parrotfishes are a sub-clade of wrasses
Parrotfish teeth are fused into a “beak” for grazing on coral

Lophiiformes

Mass is mostly head and jaws, large mouths
Lure used to attract prey: frogfish lures mimic invertebrates, anglerfish lures emit light
Illicium (rod/stalk): modified dorsal spine controlled by muscles
Esca (bait/lure): luminescent organ housing symbiotic bacteria

Tetraodontiformes

Many fins lost or functionally lost, clavus: a pseudocaudal fin acts as a rudder

Fish Swimming Modes

Body-Caudal Fin (BCF) Swimming:
- Anguilliform swimming (eels):
  - Swimming with most of the body and caudal fin
  - High maneuverability and flexibility
  - Slow speed, low hydrodynamic efficiency
  - Swimming interrupted by periods of inactivity
  - Cylindrical and elongate body, pointed head, paired fins reduced or absent
- Carangiform swimming (jacks):
  - Swim with posterior body region and caudal fin
  - Intermediate maneuverability, flexibility, and hydrodynamic efficiency
  - Slow-medium speed; near-constant swimming
  - Laterally compressed
  - Narrow in front of tail, rounded or blunt head, pointed fins
- Thunniform swimming (tunas):
  - Swim with caudal fin
  - Intermediate body flexibility
  - Low maneuverability, high hydrodynamic efficiency
  - Constant medium-to-high speed swimming
  - Laterally compressed, narrow in front of tail, pointed head, pointed fins
- Ostraciform swimming (boxfishes):
  - Swim with caudal fin
  - Very little body flexibility
  - High maneuverability, very slow speed, low hydrodynamic efficiency
  - Large pectoral fins used for steering
  - Other fins reduced or vestigial
Median-Paired Fin (MPF) Swimming:
- Labriform swimming (wrasses):
  - Swim with pectoral fins
  - Intermediate body flexibility
  - Intermediate maneuverability, slow speed
  - Intermediate hydrodynamic efficiency
  - Swimming in bursts
  - Laterally compressed, long, tapered pectoral fins
- Rajiform swimming (rays):
  - Swim with pectoral fins, low body flexibility
  - Low maneuverability, slow speed, high stability
  - Low-to-high hydrodynamic efficiency
  - Dorso-ventrally compressed, expanded pectoral fins
  - Benthic species have dorsally positioned eyes
- Gymnotiform swimming (knife fish):
  - Swim with anal fin
  - Low body flexibility, high maneuverability, slow speed
  - Anal fin expanded along the body
  - Laterally compressed
- Amiiform swimming (bowfin):
  - Swim with dorsal fin
  - Low body flexibility, high maneuverability, slow speed
  - Elongate, tubular shape
- Balistiform swimming (triggerfish):
  - Swim with dorsal and anal fin
  - Low body flexibility, high maneuverability, slow speed
  - Tapered head and body (triggerfish and pufferfish)
  - Laterally compressed (triggerfish)
  - Rounded body (pufferfish)

Caudal Fin Types

Protocercal:
- Undifferentiated, symmetrical
- Lampreys and hagfishes
Heterocercal:
- Unequal-lobed (upper larger), asymmetrical
- Passively generated some lift
- Sharks and sturgeons
Hypocercal:
- Asymmetrical: bottom larger
- Uncommon
- Flying fish: passive drag to keep from drifting
Homocercal:
- Symmetrical, most common
- Most variable in shape
- Tunas and wrasses
- Sub-types:
  - Rounded (sunfishes)
  - Truncate (darters)
  - Lunate (tunas)
Hemihomocercal:
- Asymmetrical (without lobes), abbreviated homocercal
- Bowfin and gar

Locomotion

Most species use their pectoral fins to some degree:
- Carangiform/thunniform: use long stiff pectoral fins for steering at moderate-to-high speeds
- Ostraciform/balistiform: use flexible pectoral fins to supplement dorsal and anal fins for propulsion
Some species rarely use their caudal fin, but will in certain situations:
- Labriform/amiiform swimmers: use tail to generate a burst of propulsion
Anguilliform swimmers: usually benthic, often complex habitat
Carangiform/thunniform swimmers: pelagic, open water away from structures
Ostraciform swimmers: coral reefs, but not necessarily benthic
Labriform swimmers: coral reefs, rarely benthic
Rajiform swimmers:
- Undulating pelvic fins: benthic, simple or moderately complex, often sandy areas (many species burrow)
- Oscillating pelvic fins: pelagic, open water
Gymnotiform swimmers: complex habitat, but not benthic
Amiiform swimmers: variable habitat, complex or simple
Balistiform swimmers: complex habitat

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Test your knowledge on elasmobranchii, including sharks and their unique characteristics. This quiz covers various aspects of their biology, including respiratory systems, feeding behaviors, and adaptations. Dive into the fascinating world of marine life and understand the diversity of species across different environments.