Sharks Biology Quiz

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Questions and Answers

What type of tail do most sharks possess?

A diphycercal tail, tapering to a point.

A homocercal tail, with equal upper and lower lobes.

A lunate tail, with a crescent shape.

A heterocercal tail, with a larger dorsal lobe. (correct)

What is the approximate sensitivity of a shark's olfactory sense compared to a human's?

1000 times more sensitive

10 times more sensitive

100 times more sensitive (correct)

50 times more sensitive

Which of these shark groups includes the largest, surface filter-feeding sharks?

Galeomorphii (correct)

Cookie-cutter sharks

Megamouth sharks

Squalomorphii

Which of these sharks would you expect to see in a cold, deep water environment?

Spiny Dogfish (D) Signup and view all the answers

What is the primary function of a shark's nictitating membrane?

To protect the eye from abrasion during feeding or aggressive encounters. (D) Signup and view all the answers

What is the primary function of the modified pelvic fins in male sharks?

To facilitate internal fertilization. (D) Signup and view all the answers

What is the function of the lateral line in sharks?

It detects turbulence and vibrations in the water, helping them find prey. (A) Signup and view all the answers

Which of the following is true regarding the olfactory lobes of sharks?

Sharks in deep-sea and migratory species tend to have large olfactory lobes. (B) Signup and view all the answers

How is the male's right clasper oriented during mating in Batoidea?

It is bent at a 90° angle to the body. (C) Signup and view all the answers

Which of the following best describes a shark's lens?

Spherical and rigid. (B) Signup and view all the answers

What is the process by which some sharks like the Mako and Great White, maintain a higher body temperature than the surrounding water?

Regional heterothermy. (B) Signup and view all the answers

What is the primary function of the enlarged pectoral fins in Batoidea?

For locomotion. (D) Signup and view all the answers

How are a shark's jaws articulated to the braincase?

By ligaments (A) Signup and view all the answers

Which of the following best describes the typical feeding strategy of most Batoidea?

Bottom-dwelling ambush hunting. (A) Signup and view all the answers

Which term refers to the process where an embryo receives nourishment primarily from the yolk?

Lecithotrophy (B) Signup and view all the answers

What is a distinctive feature of the tail found in some Batoidea, such as sting rays?

A whip-like shape with a venomous spine. (A) Signup and view all the answers

What is the primary function of the countercurrent heat exchange system in sharks?

Capture heat produced by muscles to warm the body, including eyeballs. (B) Signup and view all the answers

What is meant by the term 'apex predator' in the context of sharks?

They are at the top of the food web and are not commonly preyed upon themselves. (B) Signup and view all the answers

What is a notable method of water intake during respiration in Batoidea?

Through enlarged dorsal spiracles. (C) Signup and view all the answers

What does a planktivorous shark primarily consume?

Floating microorganisms. (C) Signup and view all the answers

Which of these methods of prey capture is NOT mentioned explicitly in the text?

Stunning (D) Signup and view all the answers

How do sharks achieve focus when viewing their prey?

By using muscles to move the entire lens forward or backward. (A) Signup and view all the answers

What is the primary function of the tapetum lucidum in a shark's eye?

To improve vision in low-light conditions by reflecting light back through the retina. (B) Signup and view all the answers

What is the function of the Ampullae of Lorenzini in sharks?

Detecting the electric fields produced by other animals. (B) Signup and view all the answers

What is the main fluid filling the membranous labyrinth in a shark?

Endolymph, which is similar to seawater (C) Signup and view all the answers

How do otoliths in the shark's inner ear contribute to its balance?

By shifting when the animal changes direction or experiences vibrations, stimulating hair cells. (B) Signup and view all the answers

In which spatial planes can sharks detect motion using their semicircular canals?

Motion in all 3 spatial planes. (A) Signup and view all the answers

What is typically a shark's behavior towards unfamiliar prey?

Sharks will circle the prey assess it before attacking. (B) Signup and view all the answers

Which senses are most crucial for a shark during the final moments of prey attack when their vision is compromised?

Electroreception and smell. (B) Signup and view all the answers

Which characteristic is most useful in distinguishing between skates and rays?

Skates are oviparous, while rays are viviparous. (B) Signup and view all the answers

What is the primary method that electric rays use to capture prey?

Stunning prey with an electrical discharge from specialized muscles. (A) Signup and view all the answers

Which of the following best describes the reproductive strategy of chimaeras?

They are oviparous, laying two eggs simultaneously multiple times in a season. (C) Signup and view all the answers

What is a key synapomorphy of the Holocephali subclass that includes chimaeras?

A bony plate covering gill arches called an operculum. (C) Signup and view all the answers

What is a common characteristic of the habitat of chimaeras?

They live in deep ocean waters just off the seafloor at depths of 500m or more. (C) Signup and view all the answers

Which of the following is a defining characteristic of Holocephali?

A single external gill opening covered by an operculum (A) Signup and view all the answers

What is the primary function of placoid scales in Chondrichthyes?

To reduce friction and direct water flow around the body (B) Signup and view all the answers

How do Chondrichthyes address osmotic regulation in a marine environment?

By retaining nitrogenous compounds in their body fluids (C) Signup and view all the answers

What is the composition of the outer layer of a placoid scale?

Vitrodentine (A) Signup and view all the answers

Which skeletal material is characteristic of Chondrichthyes?

Cartilage that is mineralized differently than bone (A) Signup and view all the answers

In Chondrichthyes, how are teeth typically replaced?

By the continuous eruption of teeth from a whorl-like structure (D) Signup and view all the answers

Which jaw structure is characteristic of extant elasmobranchs?

Hyostylic jaw with an extendable and retractable upper jaw (D) Signup and view all the answers

What is the function of the bioluminescent photopores found in some Chondrichthyes?

To illuminate spines and disrupt the body outline (C) Signup and view all the answers

How does the biofluorescence observed in some sharks work?

They absorb blue light and re-emit it as green light. (C) Signup and view all the answers

What is the function of 'claspers' found in male Chondrichthyes?

To assist with internal fertilization (D) Signup and view all the answers

Which of these characteristics is unique to Elasmobranchii?

Ventral mouth with a protrusible upper jaw (A) Signup and view all the answers

What does the lateral line system of elasmobranchs primarily detect?

Vibrations in the surrounding water (A) Signup and view all the answers

How does the skin feel when stroking a shark from head to tail, compared to tail to head?

Smooth from head to tail, rough from tail to head (B) Signup and view all the answers

What makes the teeth of Chondrichthyes different from bony fish?

They are not embedded, but sit upon the cartilage. (D) Signup and view all the answers

What is the name of the modified scales on the skin of a shark?

Placoid scales (A) Signup and view all the answers

Which of the following is NOT a method of prey capture used by sharks?

Venom injection (A) Signup and view all the answers

What is the primary function of the claspers in male sharks?

To hold onto the female during mating (D) Signup and view all the answers

Which of the following describes the type of reproduction in sharks that relies solely on the yolk for the embryo's nourishment?

Lecithotrophy (C) Signup and view all the answers

What is the function of the countercurrent heat exchange system in mackerel sharks?

To regulate body temperature (A) Signup and view all the answers

Which of these sharks is an example of a homeothermic species?

Mako (A) Signup and view all the answers

What is the primary function of the teeth in sharks?

To catch prey (B) Signup and view all the answers

Which of the following is TRUE about the reproduction of sharks?

Sharks lay eggs that hatch outside the mother's body (A) Signup and view all the answers

Which shark species would you expect to be most likely found in deep, cold water?

Shortfin Mako Shark (C) Signup and view all the answers

Which of the following best describes the body shape of most sharks?

Fusiform with a heterocercal tail (B) Signup and view all the answers

Considering the chemoreception capabilities of sharks, which species would likely possess the largest olfactory lobes relative to their brain size?

A migratory deep-sea shark (C) Signup and view all the answers

The 'third eyelid' in some sharks provides protection during which activity?

When feeding or encountering another shark (B) Signup and view all the answers

Which of these shark groups would you NOT expect to see near the surface of the ocean?

Squalomorphii (B) Signup and view all the answers

Based on information in the text, which of these sharks is NOT a filter feeder?

Great white sharks (C) Signup and view all the answers

Which of the following characteristics is NOT primarily involved in a shark's detection of prey via chemoreception?

Lateral line (D) Signup and view all the answers

A shark that primarily feeds on plankton would be described as:

Planktivorous (B) Signup and view all the answers

Which shark species listed in the text demonstrates a notable size difference between males and females?

The content does not specify such a difference. (A) Signup and view all the answers

Which feature distinguishes Holocephali from Elasmobranchii?

A single external gill opening covered by an operculum (C) Signup and view all the answers

What is the primary function of the large, lipid-filled liver found in Chondrichthyes?

To maintain neutral buoyancy (C) Signup and view all the answers

The scales of Chondrichthyes are also referred to as dermal denticles, because they:

Have a similar structure to their teeth (C) Signup and view all the answers

How does the tooth replacement mechanism differ in Chondrichthyes compared to bony fishes?

Their teeth form in a whorl and are continuously replaced (B) Signup and view all the answers

What type of jaw structure is characterized by the upper jaw being fused to the cranium with the lower jaw pivoting?

Holostylic (D) Signup and view all the answers

What is a key characteristic of placoid scales in terms of their growth?

They do not increase in size but new ones are added. (A) Signup and view all the answers

What is the function of biofluorescence in sharks?

To absorb blue light and emit green light (D) Signup and view all the answers

Which of the following is a synapomorphy of Elasmobranchii?

Ventral mouth and protrusible upper jaw (A) Signup and view all the answers

The primary function of the 'claspers' in male Chondrichthyes is for:

Reproduction via internal fertilization (B) Signup and view all the answers

What is the benefit of placoid scales being slanted towards the tail of a shark?

To reduce friction while swimming (C) Signup and view all the answers

What is the effect of stroking a shark from tail to head versus head to tail?

It feels smooth from head to tail, and like sandpaper from tail to head (D) Signup and view all the answers

Which of the following best describes the skeleton of most Chondrichthyes?

Composed of cartilage and calcified vertebrae and teeth (B) Signup and view all the answers

What is the significance of the 'spiral valve' in the elasmobranch digestive system?

It increases the surface area for nutrient absorption (C) Signup and view all the answers

Which type of jaws do extant Chimaeras possess?

Holostylic jaws (A) Signup and view all the answers

What are Chondrichthyes best known to retain for osmotic regulation in the marine environment?

Nitrogenous compounds (C) Signup and view all the answers

What is a common hunting strategy employed by Batoidea?

Ambushing prey while buried in sand (D) Signup and view all the answers

Which feature distinguishes the teeth of Batoidea from those of many other fish?

Large, flat teeth for crushing prey (C) Signup and view all the answers

How do manta rays primarily obtain their food?

Filter feeding on plankton (B) Signup and view all the answers

What adaptation allows Batoidea to take in water for respiration?

Dorsal spiracles that provide a direct path for water intake (B) Signup and view all the answers

Which feature is common among sting rays and assists in their defense?

Whip-like tail with saw-toothed venomous spine (C) Signup and view all the answers

What distinguishes the reproductive strategy of rays from that of skates?

Rays are viviparous, while skates are oviparous. (D) Signup and view all the answers

What feature is common in the tail structure of rays compared to skates?

Rays might possess venomous spines in their tails. (B) Signup and view all the answers

Which statement is accurate regarding the hunting behavior of electric rays?

Electric rays ambush prey during the day after stunning them. (C) Signup and view all the answers

Which characteristic is unique to chimaeras among their subclass features?

They possess crushing plate teeth. (C) Signup and view all the answers

What is a key characteristic of chimaeras' life history plan?

They reproduce only one time per year with several young. (C) Signup and view all the answers

What role does the tapetum lucidum play in a shark's vision?

It reflects light to enhance low-light vision. (A) Signup and view all the answers

What adaptations allow sharks to detect electric fields produced by other animals?

Ampullae of Lorenzini located in their snouts. (B) Signup and view all the answers

How does a shark's inner ear contribute to its predatory abilities?

It detects water-borne vibrations for better targeting. (D) Signup and view all the answers

During an attack on prey, what does a shark primarily rely on when it is blind?

Electroreception and sense of smell. (B) Signup and view all the answers

What is the purpose of otoliths in the shark's sacculus?

To trigger hair cells in response to direction changes. (A) Signup and view all the answers

Which feature of shark vision is most important for hunting in low-light environments?

Reflective tapetum lucidum behind the retina. (D) Signup and view all the answers

What type of prey behavior is commonly observed in sharks when they encounter unfamiliar prey?

They circle the prey before deciding to engage. (C) Signup and view all the answers

How do sharks adjust the focus of their vision?

By moving the entire lens forward or backward. (D) Signup and view all the answers

Study Notes

Chondrichthyes: Cartilaginous Fish

Divided into two groups: Elasmobranchii and Holocephali
Elasmobranchii have multiple gill openings on each side of the head
Have independently mobile upper jaws
Includes sharks, rays, and skates
Sharks are torpedo-shaped with 5-7 gill openings on each side of the head
Rays and skates are dorsoventrally flattened with 5 pairs of gill openings on the ventral surface
Holocephali have an undivided head due to a single, external gill opening covered by an operculum
Includes chimaeras, rabbitfishes, ratfishes, and ghost sharks
Fish-like body with a long flexible tail
Some have large eyes and broad tooth plates, similar to that of a rabbit

Megalodon

Largest shark
Exhibits pre-birth cannibalism

Distinctive Characteristics of Chondrichthyes

Approximately 970 extant species
Cartilaginous chondrocranium, jaws, gill arches, vertebrae, and fin supports
Bony tissues include fin spines, teeth, scales (dermal origin)
Lost skeletal plates seen in acanthodians, but have exoskeletons of placoid scales composed of dentine, enameloid, and bone
Male pelvic fins are modified into claspers
Broad, wing-like pectoral fins generate "lift" during forward swimming
Large lipid-filled liver maintains neutral buoyancy
Retain nitrogenous compounds for osmotic regulation in marine environments

Tooth Replacement in Chondrichthyans

Teeth are not embedded in the jaw like bony fish
Teeth are replaced in whorls as they wear down and fall out
Skeletons break down after death (due to cartilage composition)
Teeth are composed of bone, making fossils easily identifiable

Chondrichthyan Jaws

Primitive chondrichthyans possess autodiastylic jaws, with the upper jaw firmly attached to the cranium
Primitive elasmobranchs have amphistylic jaws, with the anterior end attached to the cranium and the posterior end supported by the hyomandibular arch
Extant elasmobranchs have hyostylic jaws, allowing the upper jaw to extend and retract during feeding
Extant chimaeras possess holostylic jaws, with the upper jaw fused to the cranium and the lower jaw having pivots

Chondrichthyan Skin

Composed of placoid scales, bony, spiny projections with enamel-like coverings
Similar structure to teeth; referred to as dermal denticles
Slanted toward the tail, aiding in water flow around the body, reducing friction
Stroking a shark from head to tail feels smooth; from tail to head feels like sandpaper
Placoid scales do not increase in size, but instead new scales are added between older ones

Chondrichthyan Scales

Each scale consists of a flattened rectangular base plate embedded in the fish.
Variously developed structures, like spines, project posteriorly on the surface
Composed of a vascular inner pulp core, a middle dentine layer, and a hard enamel-like outer vitrodentine layer

Bioluminescence

Photopores produce light on shark bodies
Illuminate spines, breaking up the visual outline of the body
Lantern sharks, viper dogfish, and other species exhibit bioluminescence

Biofluorescence

Molecules in shark skin absorb blue light and transform it into green light
Likely used for communication between sexes

Subclass: Elasmobranchii - Sharks, Rays, Skates

Approximately 937 extant species, primarily marine
Ventral mouth; upper jaw is not fused to the chondrocranium (protrusible)
Skin with placoid scales
5 to 7 pairs of gills leading to exposed gill slits
No swim bladder; liver contains squalene (oil)
Digestive system with a J-shaped stomach and intestine with a spiral valve
Some species are viviparous with a 2-year gestation period
Have a lateral line to detect vibrations

Elasmobranchii - Sharks

Approximately 45% of elasmobranchs are sharks, sawfishes, and guitarfishes
Jaws are moveably articulated to the braincase (chondrocranium) by ligaments.
Fusiform body shape, with a heterocercal tail (dorsal epichondral lobe longer than ventral hypochondral lobe)
Very keen olfactory sense (occupying 2/3 of the brain area)
Can detect one drop of blood in 100 billion drops of water (100x more sensitive than humans)

Sharks (Selachii)

Galeomorphii (mostly large sharks): great white sharks (carnivorous), hammerhead sharks (carnivorous), whale sharks (surface filter feeder), basking sharks (surface filter feeder), megamouth sharks (deep filter feeder), mako sharks (smaller), horn sharks (smaller)
Squalomorphii (usually smaller sharks): cow sharks (largest), angel sharks, spiny dogfish, green lantern sharks (cold, deep water), cookie cutter sharks (deep water)

Size Range of Sharks

Wide range of sizes, from small to extremely large, such as whale sharks.

Skates vs. Rays

Skates (generally) have circular or rounded bodies, while rays have kite-shaped bodies
Skates have thick tails without spines, whereas rays have whip-like tails, sometimes with spines
Skates are oviparous (mermaid's purse), while rays are viviparous (nonplacental)

Electric Rays

Specialized muscles on either side of the head can deliver a strong electric shock to stun prey
Ambush hunters that surge upward from the sand, stunning prey with their pectoral fins during the day
At night, they hover above the sand and descend, startling prey below them

Subclass: Holocephali - Chimaeras

Approximately 50 extant species, all marine
Operculum (bony plate) covering gill arches
Upper jaw solidly fused to the braincase (holostylic)
Some species have a tenaculum (clasper) on the forehead
Skin without scales
Teeth modified into crushing plates

Chimaeras

Live off the seafloor (500 m or more)
Usually under 1 meter long
Feed on sea anemones, jellyfish, small fish, crustaceans, and mollusks
Life histories are not well understood
Reproduce once a year, with only a few young, and are oviparous
Embryonic development takes 6-12 months
Have three forms: shortnose, longnose, and plownose

Predatory Behavior

Typically attack familiar prey immediately, but circle unfamiliar prey
Opportunistic feeders, consuming dead or weakened animals
Sensory systems such as electroreception and smell are crucial in the final stages of prey capture, making sight less important

Thermoregulation

Most sharks are poikilothermic (cold-blooded), but some pelagic species (e.g., mako shark) are homeothermic (warm-blooded)
Top: Mako sharks
Middle: Swordfish
Bottom: Great Whites

Shark Ecology

Apex predators that are key components of marine food webs

Feeding

Teeth are replaceable; multiple rows deep within the jaws
Up to 20,000 teeth can be replaced within a shark's lifetime
Carnivorous (feeding on fish or mammals) or planktivorous (filter feeding)
Inanimate objects (like metal or plastic) are often found within their stomachs

Teeth Shapes and Function

Mechanisms of prey capture include biting, ramming, and suction
Teeth are held in place by collagen
Various tooth shapes reflect different prey types and feeding strategies

Reproduction

Pelvic fins modified as claspers, creating an intromittent organ for internal fertilization
Oviparity (eggs deposited in a sac-like membrane, ancestral) / Viviparity (ova hatched internally, with nourishment supplied via umbilical connection)
Lecithotrophy (yolk supplies nourishment to embryos) / Matrotrophy (mother supplies energy)

Copulation in the Whitespotted Bamboo Shark

Male inflates siphon sacs with seawater to attract females.
Right clasper used to copulate.

Batoidea (Superorder)

Over 50% of elasmobranchs are rays and skates
Sting rays, electric rays, mantas (large fish)
Dorsoventrally flattened; enlarged pectoral fins for locomotion
Ventral gill openings; water intake through enlarged dorsal spiracles
Tail with a whip-like structure with saw-toothed venomous spines (in stingrays)

Batoidea Characteristics

Primarily bottom dwellers.
Ambush hunters that rest on the sea floor, camouflaging themselves with sand to wait for prey.
Mouths are highly protrusible for sucking prey from the substrate.
Flat teeth crush prey.
Larger rays (manta rays) are filter feeders of plankton

Chemoreception and Mechanoreception

Swimming noses have extremely low concentration detection capabilities
Migratory/deep-sea species have larger olfactory lobes; whereas, coral-reef species have small olfactory lobes
Possesses a lateral line that detects water turbulence and vibrations

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Description

Test your knowledge on the fascinating biology of sharks! This quiz covers topics such as shark anatomy, sensory systems, mating behaviors, and adaptations. Learn more about how these incredible creatures operate in their marine environments.