Aquatic Vertebrates

Question 1

Vertebrates characteristics

Answer 1

The four chordate characteristics (notochord, hollow dorsal nerve cord, pharyngeal gills, post anal tail), plus vertebral column, cranium, cranial nerves, neural crest cells, 2 pairs of appendages, ventral heart, large digestive glands, separate sexes, endocrine glands, paired kidneys

Question 2

What are neural crest cells?

Answer 2

Cells that aid in the development of many structures such as the skull, jaws, nerves, and muscles

Question 3

What is the function of having 2 pairs of appendages in vertebrates?

Answer 3

They are used for stability and locomotion

Question 4

What is the vertebrate’s circulatory system like?

Answer 4

Closed circulatory system with a ventral heart

Question 5

What is the vertebrate’s digestive tract like?

Answer 5

A complete digestive tract, that contains large digestive glands

Question 6

What are endocrine glands for in vertebrates?

Answer 6

For secreting hormones

Question 7

What are paired kidneys used for in vertebrates?

Answer 7

Fluid balance

Question 8

Aquatic vertebrates: group Agnatha

Answer 8

Jawless fishes that contain only two classes now, those are Class Myxini (marine hagfishes) and Class Cephalospidomorphi (lampreys)

Question 9

Class Myxini

Answer 9

Part of group Agnatha; Myxini are called hagfishes. There has been a debate over whether hagfishes possess vertebrae and should actually be considered vertebrates and instead be classified into clade Craniata

Question 10

Class Cephalospidomorphi

Answer 10

Part of group Agnatha; includes lampreys (true vertebrate fishes). The larval stage of sea lamprey lives in freshwater streams and is a suspension feeder. It later transforms into an adult as a parasitic marine lamprey, where it fishes with a rasping, toothy, oral disk. Lamprey lack paired fins that most other fish have, and thus are weak swimmers.

Question 11

Aquatic vertebrates: group gnathostomata

Answer 11

Evolved hinged jaws enabling them to grasp and chew their foods instead of using suctorial feeding methods. Jaws developed from modifications of the skeletal elements supporting pharyngeal gill slits. Includes class chondrichthyes

Question 12

Class Chondrichthyes

Answer 12

Part of group gnathostomata, includes sharks, rays, and skates. Possess well-developed jaws and an entirely cartilaginous skeleton. Possess paired pectoral and pelvic fins, claspers, lateral line system, spiracles, placoid scales in some, spiral valve, rectal gland.

Question 13

What is the function of paired pectoral and pelvic fins in chondrichthyes?

Answer 13

To aid the stability and maneuverability of sharks.

Question 14

What is the function of claspers in chondricthyes?

Answer 14

Used to correctly position the female’s body during internal insemination

Question 15

What is the function of the lateral line system in chondrichthyes?

Answer 15

Extends the length of the body to be used for mechanoreception (detection of movements in the water)

Question 16

What is the use of spiracles used by some sharks?

Answer 16

Located near the eyes, they are used by some sharks to supply oxygen to the eyes or draw water into the gill chambers while buried in sand

Question 17

What is the use of placoid scales in sharks?

Answer 17

Scales that are modified teeth that give skin its sandpaper texture. Shark teeth actually evolved from this structure

Question 18

What is the function of the spiral valve in sharks?

Answer 18

Used in the small intestine to increase surface area for nutrient absorption

Question 19

What is the function of the rectal gland in sharks?

Answer 19

Functions in osmoregulation by excreting excess salts from the blood

Question 20

Aquatic vertebrates: superclass osteichthyes

Answer 20

Superclass Osteichthyes are the bony fishes, characterized by their ossified skeletons. They are the most diverse group of fishes today including over 30,000 species. They possess an operculum, pectoral fins, pelvic fins, dorsal and anal fins, and swim bladder. They include classes actinopterygii and sarcopterygii

Question 21

What is the function of operculum in superclass osteichthyes?

Answer 21

A bony structure that protects pharyngeal gills and enables fishes to continue respiring without having to swim constantly

Question 22

How are Chondrichthyes similar to Osteichthyes?

Answer 22

They both contain a functional lateral line system and paired fins

Question 23

Where are the pectoral fins located in osteichthyes?

Answer 23

More lateral than ventral

Question 24

Where are the pelvic fins located in osteichthyes?

Answer 24

More anterior

Question 25

What are the dorsal and anal fins like in most osteichthyes?

Answer 25

They are more elongate and flexible

Question 26

What is the use of a swim bladder in osteichtyes?

Answer 26

In some fishes, this is used. It is an air sac used to maintain buoyancy, allowing it to be a more maneuverable fish

Question 27

cycloid scale

Answer 27

A type of scale found in some types of bony fishes such as goldfish. As the fish increases in size, growth rings called circuli can be visible in the scales and can be used to estimate the age of the fish by measuring the annuli formed in cooler months of the year.

Question 28

Actinopterygii vs Sarcopterygii characteristics

Answer 28

Two major groups of the bony fishes (osteichthyes). The main differences between the two involve the fact that actinopterygii have fins of parallel bony rays (thus called ray-finned fishes), whereas sarcopterygii (aka lobe-finned fishes), have fleshy, lobe-like fins supported by fully articulated bones.

Question 29

Actinopterygii vs Sarcopterygii evolution

Answer 29

Although the majority of existing bony fishes belong to the class Actinopterygii, members of class Sarcopterygii played an important role in the evolution of terrestrial vertebrates. Some sarcopterygii (lobe-finned fishes) have developed vascularized outpocketings of the gut, forming primitive lungs. Those lungfish share a common ancestor with tetrapods (four-legged vertebrates).