Evolutionary Adaptations in Agnatha

Questions and Answers

What is the primary function of the dorsal nerve cord in Agnatha?

Locomotion

Nervous system control (correct)

Respiration

Digestion

Which feature distinguishes the class Chondrichthyes from Agnatha?

Absence of a stomach

External fertilization

Numerous gills

Presence of jaws (correct)

In which class are the gill slits used for respiration mainly found?

Cephalospidomorphi (correct)

Mammalia

Aves

Amphibia

What is a notable reproductive characteristic of Agnatha?

Separate sexes Signup and view all the answers

How do Agnatha primarily obtain blood from their prey?

Through a buccal funnel and toothed tongue Signup and view all the answers

Which evolutionary adaptation aids Agnatha in moving through water?

Long, slender bodies with slimy skin Signup and view all the answers

What type of skeletal system do Chondrichthyes possess?

Cartilaginous Signup and view all the answers

Which subclass of mammals is primarily characterized by egg-laying?

Prototheria Signup and view all the answers

Which of the following is a common characteristic of Myxini?

Slimy skin aiding in locomotion Signup and view all the answers

What is one key feature that differentiates marsupials from other mammals?

They have an abdominal pouch. Signup and view all the answers

What is a common characteristic shared by all mammals?

They possess mammary glands. Signup and view all the answers

Which of the following statements is true regarding the prototheria subclass?

They are a connecting link between reptiles and mammals. Signup and view all the answers

Which mammal is an example of a monotreme?

Duck-billed platypus Signup and view all the answers

In which type of environment do members of the Metatheria subclass primarily live?

Primarily Australia and America Signup and view all the answers

What is a defining characteristic of the young of marsupials at birth?

They are immature and require the pouch for growth. Signup and view all the answers

What unique feature do monotremes possess that distinguishes them from other mammals?

Presence of a cloaca Signup and view all the answers

What is the primary method of reproduction in sponges?

Budding or gemmules Signup and view all the answers

Which of the following is not a subphylum of Chordata?

Echinodermata Signup and view all the answers

What are spicules made of in sponges?

Calcarious or siliceous materials Signup and view all the answers

Which of these options does not pertain to a deuterostome?

Radial cleavage Signup and view all the answers

What type of cells in sponges are responsible for feeding?

Choanocytes Signup and view all the answers

Which organism has a gastrovascular cavity?

Flatworms Signup and view all the answers

Which statement is true regarding the nervous system of sponges?

Sponges lack a definite nervous system Signup and view all the answers

How do sponges primarily facilitate gas exchange?

By diffusion and water currents Signup and view all the answers

Amphibians arose from which group of fish?

Bony fishes with lungs Signup and view all the answers

What does the term 'amphibian' refer to?

Organisms capable of living both in water and on land Signup and view all the answers

What is notable about the regeneration ability of sponges?

They can regenerate from a small fragment Signup and view all the answers

In what form is digestion accomplished within sponges?

Completely intracellularly Signup and view all the answers

Which of the following classes of vertebrates has a four-chambered heart?

Mammals Signup and view all the answers

Which of the following correctly describes the evolutionary significance of sponges?

They represent a dead end in evolution. Signup and view all the answers

Which of the following does not describe a characteristic of platyhelminthes adapted for parasitism?

Segmented body structure Signup and view all the answers

Which of the following accurately describes ectothermic animals?

They rely on external environmental conditions to manage their body temperature. Signup and view all the answers

What is a defining characteristic of amphibians regarding their limbs?

They typically have two pairs of pentadactyl limbs. Signup and view all the answers

Which of the following respiratory methods is used by adult amphibians?

Lungs and skin Signup and view all the answers

What type of circulatory system do amphibians possess?

Double circulation Signup and view all the answers

Which reproductive method is most commonly observed in amphibians?

Oviparous with external fertilization Signup and view all the answers

What is the body temperature regulation method of amphibians?

Poikilothermic Signup and view all the answers

Which of the following adaptations help amphibians transition from water to land?

Internal nares for breathing Signup and view all the answers

What type of circulatory system allows respiration through both lungs and skin in amphibians?

Double loop circulation Signup and view all the answers

What distinguishes amphibians from other vertebrates in terms of their reproductive development?

They undergo metamorphosis. Signup and view all the answers

Study Notes

Superclass Agnatha

Comprised of jawless fish, including Hagfish (Myxine) and Lamprey (Petromyzon marinus).
Five to sixteen gills are used for respiration in Myxini; Cephalospidomorphi have seven pairs with external openings.
Lacks a stomach; features a dorsal nerve cord and differentiated brain.
External fertilization occurs with no larval stage; sexes are separate.
Adaptations include long, slender, limbless body and slimy skin for reduced water resistance.
Tail with caudal fin enhances forward thrust; buccal funnel and toothed tongue adapted for blood-sucking.

Superclass Gnathostomata

Comprised of six classes: Chondrichthyes, Osteichthyes, Amphibia, Reptilia, Aves, and Mammalia.

Class Chondrichthyes

Known as cartilaginous fishes, including sharks, rays, and skates.
Possess jaws evolved from the first pair of gill arches; skeletons are largely cartilaginous.
Body shape is laterally compressed and fusiform; mouth is located ventrally.

Class Amphibia

Body forms vary, with a clear division into head and trunk.
Most have two pairs of pentadactyl limbs; some, like caecilians, lack legs.
Skin is smooth, moist, and highly vascular, often with glandular structures.
Respiration in larval stage is via gills, whereas adults use lungs and skin.
Heart has three chambers; undergoes double circulation.
Fertilization can be external or internal; most are oviparous with a metamorphic life cycle.
Temperature regulation is poikilothermic, leading to behaviors such as hibernation.

Evolutionary Adaptations in Amphibia

Significant transition from aquatic to terrestrial life.
Adaptations include limbs for movement, lungs for air breathing, and internal nares for closed-mouth breathing.
Slimy skin helps prevent desiccation.
Circulatory system adapted for lung and skin respiration; reduced skeletal mass for a lighter body.

Classification of Mammals

Divided into three subclasses: Prototheria (egg-laying), Metatheria (pouched), and Eutheria (placental).
Prototheria exemplifies a link between reptiles and mammals; features include cloaca and mammary glands.
The Duckbill platypus and Echidna are key examples of monotremes.

Subclass Metatheria - Marsupials

Females possess a pouch (marsupium) for immature young.
Young are nurtured in the pouch until maturing; significant examples include Opossum, Kangaroo, and Tasmanian wolf.

Sponges

Totally lack a nervous system; composed of various spicule shapes forming a skeletal framework.
Involuntary digestion occurs intracellularly within choanocytes, with respiration facilitated through diffusion and water currents.
Reproduction is both sexual (egg and sperm) and asexual (budding or gemmules).
Known for exceptional regenerative capabilities; evolved from protists called choanoflagellates.
Economic uses include personal hygiene, medical procedures, and architectural soundproofing.

General Features of Animals and Classification Criteria

Distinct features: multicellular, heterotrophic metabolism, specialized tissues, mobility.
Criteria for classification generally encompass anatomical, physiological, and genetic characteristics.
Radial symmetry adapts organisms to a sessile or free-floating lifestyle; bilateral symmetry allows for directional movement.

Responses to Questions

Amphibians arose from jawless fish.
Deuterostome characteristics include blastopore associated with the anus, enterocoelom, and inclusion of echinoderms and chordates.
Gastrovascular cavities are found in flatworms.
Non-chordate subphylum: Hemichordata.
Ectothermic animals (like fish) regulate body temperature externally; endothermic (like mammals) regulate internally.

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Description

This quiz delves into the unique characteristics and evolutionary adaptations of the agnatha superclass. Discover the differences in gill structures and reproductive methods of classes Myxini and Cephalospidomorphi, along with their notable examples like hagfish and lamprey. Test your knowledge of these fascinating jawless fish.