ch3.1

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What is the significance of the ability to form mineralized tissues in the skin for all vertebrates?

It is a feature of all vertebrates from ostracoderms onward.

How many times may the production of teeth or toothlike structures have evolved independently among vertebrates?

Several different times.

What changed ideas about early vertebrate interrelationships according to the text?

Accepting conodonts as vertebrates.

What is the importance of mineralized tissues in the vertebrate phylogeny?

It has changed our ideas about early vertebrate interrelationships. Signup and view all the answers

Why are the toothlike structures of conodonts and the bony dermal skeletons of ostracoderms considered to make them more derived vertebrates?

They are considered more derived due to these mineralized structures. Signup and view all the answers

What characterized the body fluids of early vertebrates and invertebrates in terms of osmolal concentration?

Approximately the same osmolal concentration as their surroundings. Signup and view all the answers

What unique feature do hagfishes possess in terms of gland openings?

Large mucous glands that open through the body wall to the outside Signup and view all the answers

What is the purpose of the slime produced by hagfishes?

To deter predators Signup and view all the answers

How do hagfishes get rid of the mass of mucus after producing it?

By making a knot in their body, scraping off the mass, and sneezing sharply Signup and view all the answers

What is the internal anatomy characteristic of hagfishes in terms of vertebrae?

They lack any trace of vertebrae Signup and view all the answers

Describe the eyes of hagfishes.

Degenerate or rudimentary and covered with a thick skin Signup and view all the answers

What type of tooth structures do hagfishes possess in their mouth?

Sharp toothlike structures made of keratin Signup and view all the answers

What innervates the heart in lampreys?

The parasympathetic nervous system (vagus nerve, X) Signup and view all the answers

How do lampreys regulate ions, water, and nitrogenous wastes?

Chloridetransporting cells in the gills and well-developed kidneys Signup and view all the answers

What prevents water from flowing out of the respiratory tube into the mouth of lampreys?

The velum Signup and view all the answers

How many pairs of gill pouches do lampreys have?

Seven Signup and view all the answers

What type of ventilation do adult lampreys use when they attach to other fishes?

Tidal ventilation Signup and view all the answers

Is the lampreys' mode of ventilation efficient at oxygen extraction?

No Signup and view all the answers

What is the function of the oral hood in lampreys?

The oral hood helps in tight attachment and rapid abrasion of the host's integument. Signup and view all the answers

Why is the tongue of lampreys not homologous with the tongue of gnathostomes?

The lamprey's tongue muscle is innervated by the trigeminal nerve, V, while the gnathostomes' tongue is innervated by the hypoglossal nerve, XII. Signup and view all the answers

What secretion from lampreys prevents the victim's blood from clotting?

An anticoagulant secreted by the oral gland prevents the blood from clotting. Signup and view all the answers

What is the primary diet of adult lampreys?

The body fluids of fishes make up the bulk of an adult lamprey's diet. Signup and view all the answers

Do lampreys generally kill their hosts?

No, lampreys generally do not kill their hosts. Signup and view all the answers

What type of species are lampreys that have nonfeeding adults?

Some small, freshwater lamprey species have nonfeeding adults. Signup and view all the answers

Where are lampreys primarily found?

Northern latitude temperate regions Signup and view all the answers

What is the reproductive behavior of nearly all lampreys?

Anadromous Signup and view all the answers

What is the feeding pattern of some specialized lamprey species?

Feeding only as larvae Signup and view all the answers

When are adult lampreys generally observed?

During reproductive activities or when captured with their host Signup and view all the answers

What are lampreys known to attach to after swimmers' skin temperature drops?

Bodies Signup and view all the answers

What vertebrate group eventually replaces the notochord with well-developed centra as a supporting rod for axial muscles?

Tetrapods Signup and view all the answers

Which two extinct groups of fishes did not have well-developed centra?

Placoderms and acanthodians Signup and view all the answers

What is the function of ribs in gnathostomes?

Supporting axial muscles used for locomotion Signup and view all the answers

In which group of reptiles and mammals are teeth set in sockets and held in place by periodontal ligaments?

Archosaurian reptiles and mammals Signup and view all the answers

What is the name given to the condition where teeth are fused to the jawbone, seen in most bony fishes and some reptiles?

Acrodont condition Signup and view all the answers

What is the term for the supporting rod for axial muscles used in locomotion that is eventually replaced by well-developed centra in some vertebrates?

Notochord Signup and view all the answers

What is the process by which lampreys construct their nest for breeding?

Attaching themselves to large rocks by their mouths and thrashing about violently Signup and view all the answers

How do lampreys ensure that the water in the nest is oxygenated?

By the turbulence created from the construction of the nest Signup and view all the answers

What is the distinctive feature of lamprey larvae in terms of their appearance and behavior?

Wormlike organisms with a large, fleshy oral hood and nonfunctional eyes hidden beneath the skin, spending years as sedentary filter feeders Signup and view all the answers

How do lampreys reproduce, and what happens to adult lampreys after breeding?

The female attaches to a rock and lays eggs while the male fertilizes them; adult lampreys die after breeding once Signup and view all the answers

What happens to lamprey larvae after hatching and leaving the nest?

They are carried downstream to backwaters and quiet banks, where they burrow into the soft mud or sand and spend years as sedentary filter feeders Signup and view all the answers

How do lamprey larvae differ from their parents, and what is their initial genus name?

Larvae are radically different, described as Ammocoetes, a distinct genus Signup and view all the answers

Describe the implications of the gnathostome body plan in terms of activity and complexity.

Basic step up in level of activity and complexity from jawless vertebrates. Signup and view all the answers

Explain the significance of the variability of the gnathostome lower jaw in the Silurian period.

Jaw forms were most variable in the Silurian when jawed fishes were not very common. Signup and view all the answers

Discuss the improvements seen in gnathostomes in terms of locomotor and predatory abilities.

Improvements in locomotor and predatory abilities. Signup and view all the answers

Explain the evidence of a second Hox gene duplication event in living jawed vertebrates.

Living jawed vertebrates show evidence of a second Hox duplication event. Signup and view all the answers

Describe the role of extinct ostracoderms in the acquisition of features in gnathostomes.

Extinct ostracoderm taxa may have acquired features that are seen in living gnathostomes. Signup and view all the answers

Explain the impact of gene duplication on the complexity of animals.

Greater amount of genetic information, perhaps necessary for building a more complex type of animal. Signup and view all the answers

What is the likely original function of jaws in early vertebrates, according to the text?

Gill ventilation Signup and view all the answers

What are some functions of jaws mentioned in the text other than predation?

Digging holes, carrying pebbles and vegetation, grasping mates during courtship and juveniles during parental care Signup and view all the answers

When are gnathostomes first known with certainty, according to the text?

Early Silurian Signup and view all the answers

What does the presence of isolated sharklike scales suggest about the origin of gnathostomes?

Middle Ordovician Signup and view all the answers

What diverse behaviors involving jaws are mentioned in the text?

Building nests, courtship, parental care Signup and view all the answers

What will be discussed later in the text regarding the likely origin of jaws?

Efficient gill ventilation rather than predation Signup and view all the answers

What is the material that vertebrate jaws are made of?

Cartilage derived from the neural crest Signup and view all the answers

In what head segment is the gnathostome jaw formed?

Second head segment Signup and view all the answers

How are the branchial arches related to the segments of the vertebrate head?

Each branchial arch corresponds to a segment Signup and view all the answers

What is the significance of envisioning the vertebrate head as a segmented structure?

Helpful for understanding jaw and gill support development Signup and view all the answers

Where do the more posterior branchial arches that form the gill supports originate?

Head segments 4 through 8 Signup and view all the answers

What is the material that forms the hyoid arch jaw supports?