Marine Biology Honors- Chapter 10

bump and bite attack

A bump and bite attack by a shark happens in deeper water to swimmers and divers. In this type of attack, the shark will bump the person before it bites, and may repeatedly bite causing deep wounds that can often lead to death.

clasper

A clasper is a modified pelvic fin on a male shark that is used for the transportation of sperm during reproduction.

dorsal fin

A dorsal fin is the unpaired fin that is on top (on the upper side) of a fish.

heterocercal tail

A heterocercal tail is a tail that is asymmetrical. For example, many sharks have caudel (or tail fins) that are hetercercal, where the dorsal lobes are longer than the ventral lobes.

hit and run attack

A hit and run attack by a shark is most often in shallow water with low visibility on surfers or swimmers that are splashing around. In this type of attack, the shark will bite and then release causing only minor lacerations and rarely leads to loss of life.

neuromast

A neuromast is a sensory receptor within the lateral line system of a shark that is used to detect vibrations in the water.

nictitating membrane

A nictitating membrane is a clear or transparent "third" eyelid. Sharks lack eyelids, but have the nictitating membrane to protect the eyes.

shark

A shark is a cartilaginous fish that is one of the top predators of the ocean. They have streamlined bodies and caudal fins that help in locomotion.

sneak attack

A sneak attack by a shark differs from the other attacks in that there is no warning before the attack. In this type of attack, like the bump and bite, the shark may repeatedly bite causing deep wounds that can often lead to death.

ampullae of Lorenzini

Ampullae of Lorenzini are organs found in sharks and other cartilaginous fish that are scattered over the tops and sides of the head and used to detect electrical currents in the water.

class Chondrichtyes

Animals in the class Chondrichthyes are cartilaginous fish such as Sharks, skates, rays, and chimeras whose skeletons ares composed entirely of cartilage. All have jaws, paired fins, and placoid scales.

Why are chimaeras given common names like ratfish?

Chimaeras are given common names like ratfish because of their appearance. They have large pointed heads and long slender tails.

chimaera

Chimaeras, often called ratfish, are cartilaginous fish that have large pointed heads and long slender tails. They have gills that are covered with an operculum. They have the oviparous reproductive mode, where their eggs are produced in a leather case.

class Cephalospidomorphi

Class Cephalospidomorphi are lamprey which are jawless fish that can inhabit both fresh and salt waters. They lack paired appendages and scales, and have skeletons made of cartilage.

class Myxini

Class Myxini are hagfish which are jawless fish that lack paired appendages and scales, and are bottom dwellers. They are invertebrates with skeletons composed entirely of cartilage.

dental plates

Dental plates are a pair of horny cusps that are used for feeding by the hagsfish. They grab their prey and the dental plates tear the flesh as it is drawn into the mouth.

elasmobranch

Elasmobranchs are one of two major groupings of cartilaginous fish that have evolved into two different body types, the streamlined body of sharks, and the flattened body of skates and rays.

Are hagfish considered to be vertebrates? Why or why not?

Even though they are cartilaginous fish, some scientists do not classify hagfish as vertebrates because they do not have vertebrae.

hagfish

Hagfish (also known as slime eels) are jawless fish that lack paired appendages and scales and are bottom dwellers. They are invertebrates with skeletons composed entirely of cartilage.

holocephalan

Holocephalans are one of two major groupings of cartilaginous fish consisting of chimaeras where the gills are covered by operculum and water is taken in through the nostrils.

If a shark stops swimming will it die? Why or Why not?

If a shark stops swimming it won't necessarily die, but it will sink. They have a buoyancy problem where many species are more dense than water. To help mitigate this issue, they have a enlarged liver that produces squalene, an oily lipid that helps to offset the difference in density.

Why is it not a concern if a shark looses teeth?

It is of no concern if a shark loses a tooth, because they are constantly being replaced by teeth from the inner rows, either a single tooth, or an entire row depending on the species. Some estimates indicate that a shark can produce 30,000 teeth in its lifespan.

lamprey

Lamprey are jawless fish that can inhabit both fresh and salt waters. They lack paired appendages and scales, and have skeletons made of cartilage.

olfaction

Olfaction is the sense of smell. For a shark, a large percentage of the brain is responsible for olfaction detection, through the receptors (sacs or pits) located in front of the mouth.

viviparity

One of three modes of reproduction in sharks where the eggs hatch within the mother. In this mode, the embryo feeds on the mother's "uterine milk" as opposed to other embryos like that in oviviparity.

oviparity

One of three reproductive modes of sharks which is the most primitive. In this mode, the eggs are laid in a protective case outside of the body and attached to hard surfaces on the sea floor. Sharks that are produced in this mode are smaller because of a lack of nutrients available.

Phylum Chordata

Phylum Chordata contain animals that have at some point in their lives a notochord (or skeletal rod), pharyngeal gill slits, a dorsal hollow nerve cord, and a tail that extends past the digestive tract.

placoid scale

Placoid scales are sand-paper like scales found on cartilagionous fish and resemble the teeth.

ray

Rays are cartilaginous fish with flattened bodies, enlarged pectoral fins, smaller dorsal and caudal fins, and eyes and spiracles on top of their heads. They move by flapping their pectoral fins like a bird, up and down.

Why are sharks called swimming noses?

Sharks are called swimming noses because 2/3 of their brain is used in the processing of olfactory information and can detect accurately one drop of blood per million parts of water, therefore they are able to easily detect their prey.

Do sharks sleep? Explain your answer. Do not answer just "yes" or "no".

Sharks do not sleep in the conventional sense, but they do have periods of activity and rest. Some species, such as the nurse shark have spiracles which serve as an opening for water entering the gill chamber.

What three species of sharks are responsible for the most attacks on humans?

The three species of sharks that are responsible for the most attacks on humans are the white shark, the tiger shark and the bull shark, which all feed on large marine mammals, sea turtles and large fish.

rectal gland

The rectal gland of sharks is one of the osmoregulatory organs that empties the intestines of excess salt, specifically sodium chloride.

spiral valve

The spiral valve is found in the intestine of a shark and is used to slow down the movement of food and increasing the surface area to allow for nutrient absorption.

What are the different roles or functions placoid scales?

The different roles and functions of placoid scales are that some are found on the teeth of cartilaginous fish, and some are used for protection on the skin and are formed as spines or large denticles on the backs of skates and rays.

lateral line system

The lateral line system in a shark is a sensory organ consisting of canals that travel down both sides of the body and open to the outside, and neuromasts used to detect movement in the water. They can detect tiny vibrations to find prey or avoid danger.

What is the likelihood that you will be attacked by a shark? Give the numbers or statistics.

The likelihood of being attacked by a shark is not great. The annual risk of death is 47 times less than that of getting struck by lightening, as most species of sharks are timid. Less than 10% of the ~400 species of sharks have had documented attacks on humans. Additionally, there are a reported 100 attacks per year, and only 15 fatalities.

ovoviviparity

The most common reproductive mode of the shark, where the eggs hatch inside of the mothers uterus. In this mode, the sharks feed on the yolk, unfertilized eggs and other embryos resulting in often only a single pup.

pectoral fin

The pectoral fin is a paired fin found on the side of the fish toward the head, used in stabilization and steering.

pelvic fin

The pelvic fin is a paired fin found on the underside of a fish and is used in steering.

Sharks are well adapted for a predatory lifestyle due to their complex sensory systems. What is the role of each system in this lifestyle: A. vision B. Olfaction C. Lateral line canal D. Ampullae of Lorenzini

Sharks have a complex sensory system that includes the following: a. Vision - sharks do not have eyelids, they have a nictitating membrane or clear/transparent membrane that protects their eyes. They have both rods and cones which means that they can see in color. b. Olfaction - A large percentage of the brain is responsible for olfaction (sense of smell) detection, through the receptors (sacs or pits) located in front of the mouth. Their olfactory process is well developed and evolved so that they can detect the presence of blood with great accuracy. They are referred to as "swimming noses". c. Lateral line canal - a sensory organ consisting of canals that travel down both sides of the body and open to the outside, and neuromasts used to detect movement in the water. They can detect tiny vibrations to find prey or avoid danger. d. Amullae of Lorenzini - organs found in sharks and other cartilaginous fish that are scattered over the tops and sides of the head and used to detect electrical currents in the water made by muscle movements of their prey. .

How are skates and rays adapted for a bottom existence?

Skates and rays are adapted for bottom existence by the location of the spiracles on the dorsal surface and the gill slits on the ventral side. This ensures that the water is drawn through the spiracle and passes over the gills to prevent sand or debris from clogging the gill.

skate

Skates are similar to rays in that they are cartilaginous fish with flattened bodies, enlarged pectoral fins, smaller dorsal and caudal fins, and eyes and spiracles on top of their heads, but they do not have venomous spines and are somewhat smaller than rays.

slime eel

Slime eels are hagfish that are jawless fish that lack paired appendages and scales, and are bottom dwellers. They are invertebrates with skeletons composed entirely of cartilage.

What strategies can be used to avoid a shark attack?

Some strategies that can be used to avoid a shark attack are to avoid areas where people are fishing or where there may be blood or human waste in the water, don't swim at night or where the water has low visibility, and don't wear shiny jewelry as the shark might mistake it for shiny scales of a fish.

spiracle

Spiracles are the small openings that are found behind the eyes of skates and rays that are used to allow water to enter the gill chamber when the animal is at rest.

squalene

Squalene is an oily lipid produced in the liver of sharks to offset their density and keep them from sinking.

subclass Holocephali

Subclass Holocephali are chimaeras which are a cartilaginous fish, often called ratfish, that have large pointed heads and long slender tails.

What are the advantages of having jaws and paired fins?

The advantages of having jaws and paired fins are that they animals with these adaptations could move in differing depths for food, were faster and could out compete with the more primitive fish. Jawed fish could eat a more varied diet and are not having to scavenge food on the bottom of the ocean.

anal fin

The anal fin is the unpaired, or single fin of a fish that sits behind the anus.

caudal fin

The caudal fin is another name for the tail fin, and is used for propulsion. On a shark, the caudal fin has a dorsal lobe that is longer than the ventral lobe (known as heterocercal).

What characteristics are shared by the members of class Chondricthyes?

The characteristics shared my members of the class Chondrichthyes are that they are cartilaginous fish such as Sharks, skates, rays, and chimaeras whose skeletons are composed entirely of cartilage. All have jaws, paired fins, and placoid scales.

What characteristics are shared among the animals in the phylum Chordata?

The characteristics that are shared among all animals in the phylum Chordata are that at some point in their lives have had a notochord (or skeletal rod), pharyngeal gill slits, a dorsal hollow nerve cord, and a tail that extends past the digestive tract.

What characteristics were shared by the earliest fish species?

The characteristics that are shared by the earliest fish species is that they lacked both jaws and paired fins.

What defense mechanisms are used by: A. Electric rays B. Sting rays C. Sawfish

The defense mechanism used by electric rays are that they have a pair of electric organs in their head that help to navigate and stun their prey with a voltage up to 220. The defense mechanism of sting rays are the venomous barbs that are connected to poison glands. They can whip their tail and puncture the skin of their prey causing pain, swelling and even death. The defense mechanism used by sawfish is the series of barbs along their pointed beak. They can shake there head sideways to cause an injury.

Describe the difference between skates and rays with respect to: A. Swimming behavior B. Tail structure C. Size D. Reproductive strategies

There are differences between skates and rays. For example A. swimming behavior the rays swim by moving their fins up and down, like a bird flapping, whereas the skates create a wave from the forward to edge of the fin to the back, allowing them to glide. B. Tail structure - Rays have tails that are streamlined and have venomous barbs, whereas the skates have smaller, fleshier tails with no spines. C. Size - Rays tend to be much larger than skates. D. Reproductive Strategies - Rays are oviviparous, where the eggs are hatched inside the ray, and skates are oviparous, where the eggs are released in an egg case called the mermaid's purse.

urea

Urea is the waste product of protein metabolism that is retained within the internal fluids of sharks to offset the salt water found in the ocean.

What is the smallest concentration of blood in the water that a shark can detect?

Using their well developed olfactory system, including receptors found in front of the mouth, sharks can detect one drop of blood diluted in one million parts of water and find the source.

vertebrae

Vertebrae are a series of bones or cartilages that encase and protect the spinal cord as well as help support the body of vertebrate animals.

How are vertebrates distinguished from other chordates?

Vertebrates are distinguished from other chordates in that they have vertebrae (or spinal cords that are supported by a series of bones or cartilage).

vertebrate

Vertibrates are animals such as fish, reptiles, mammals, and birds that have a spinal cord surrounded by vertebrae, or bones and cartilage.