Vertebrates: Characteristics and Class Cyclostomata

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Questions and Answers

Which characteristic is exclusively associated with vertebrates and not observed in protochordates?

Replacement of the notochord by a vertebral column. (correct)
Presence of a notochord at some stage of development.
A post-anal tail extending beyond the anus.
Bilateral symmetry and a coelom.

How does the circulatory system of cyclostomes (Agnatha) differ significantly from that of other fish classes (Chondrichthyes and Osteichthyes)?

Cyclostomes have a cartilaginous heart, whereas other fish have a bony heart.
Cyclostomes have a two-chambered heart, while other fish have a three-chambered heart.
Cyclostomes possess an open circulatory system, unlike the closed systems in other fish.
Cyclostomes have a closed circulatory system. (correct)

A researcher discovers a new aquatic vertebrate species possessing placoid scales modified into backwardly directed teeth. Based on this feature, to which class does this species most likely belong?

Agnatha
Osteichthyes
Amphibia
Chondrichthyes (correct)

Which of the following best explains why adult lampreys migrate from marine environments to freshwater environments?

To spawn, after which the adults die and the larvae undergo metamorphosis before returning to marine environments. (B) Signup and view all the answers

How does the absence of a swim bladder in Chondrichthyes influence their behavior and survival, and what compensatory mechanism do they employ?

It causes them to sink if they stop swimming, and they must constantly swim to maintain their position in the water column. (D) Signup and view all the answers

How does the persistent notochord in Chondrichthyes directly influence their physiological capabilities, especially when contrasted with the vertebral column found in Osteichthyes?

It restricts their range of motion and maneuverability compared to bony fishes. (A) Signup and view all the answers

In what way does the presence or absence of an operculum in fish species most significantly impact their respiratory efficiency and adaptability to varying aquatic environments?

The absence of an operculum necessitates continuous swimming to facilitate water flow over the gills, limiting the fish to constant motion. (A) Signup and view all the answers

Considering the reproductive strategies of Chondrichthyes, how does viviparity, coupled with internal fertilization via claspers, confer an evolutionary advantage in challenging marine environments?

It provides increased parental care and protection of developing embryos, enhancing offspring survival rates. (A) Signup and view all the answers

How does the integration of electric organs or poisonous sting organs within the predatory strategies of certain Chondrichthyes species reflect an evolutionary adaptation to specific ecological niches?

It reduces their reliance on visual hunting techniques in low-visibility environments. (C) Signup and view all the answers

Given the diverse habitats of Osteichthyes—ranging from marine to fresh water and even specialized pet environments—how do their osmoregulatory mechanisms differ to maintain homeostasis in varying salinity concentrations?

Marine species actively excrete excess salts through specialized gill cells, while freshwater species efficiently absorb ions to compensate for loss. (D) Signup and view all the answers

Flashcards

What is a vertebrate?

Animals with a notochord replaced by a vertebral column.

What are Agnathostoma?

Vertebrates lacking jaws, possessing a circular, suctorial mouth.

What are Gnathostome?

Vertebrates possessing jaws.

What are Pisces?

Aquatic vertebrates with scales, fins, and 2-chambered hearts; respiration via gills and are cold blooded.