Bio310 – Fish Skeleton and Evolution

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Questions and Answers

What type of bone develops directly into bone without any cartilage precursor?

Dermal bones (correct)

Cartilage bones

Endochondral bones

Chondrichthyes bones

How many skull bones do humans have compared to ancient actinopterygians?

150

100

28 (correct)

What is the primary evolutionary trend observed in the skulls of ancient actinopterygians to advanced teleosts?

Fusion and reduction in bony elements (correct)

Addition of more distinct skull bones

Development of more cartilage elements

Increase in size and weight of bones

Which of the following statements about lampreys is true?

They lack a dermal component in their cranial skeleton. Signup and view all the answers

In the evolution of vertebrate skeletons, dermal bone serves which of the following functions?

Armor in various forms and locations Signup and view all the answers

What is the primary function of the splanchnopleur layer in vertebrate embryos?

Development of the gut Signup and view all the answers

Which structure is associated with primary somatic segmentation?

Myomeres Signup and view all the answers

What evolutionary advantage did the ability to capture larger, more active prey provide to vertebrates?

Greater survival and adaptability Signup and view all the answers

What distinguishes primary splanchnic segmentation from secondary splanchnic segmentation?

Secondary segmentation involves structural adjustments for gill slits Signup and view all the answers

What is one of the main roles of the somatopleur layer in vertebrate embryos?

Carrying out locomotion functions Signup and view all the answers

What is the primary adaptation of pharyngeal gill slits in vertebrates?

Facilitation of water elimination during feeding Signup and view all the answers

Which of the following best describes the relationship between the somatopleur and the gut?

Somatopleur surrounds the gut Signup and view all the answers

Which statement accurately describes secondary splanchnic segmentation?

It involves structures that evolved later to support gill slits Signup and view all the answers

Which group of fish was the first vertebrates to possess true hinged jaws?

Placoderms Signup and view all the answers

Which characteristics are unique to vertebrates as synapomorphies?

Neural crest cells Signup and view all the answers

Which of the following groups includes all bony fishes?

Osteichthyes Signup and view all the answers

What type of traits do basal groups of Actinopterygii exhibit?

Many plesiomorphic traits Signup and view all the answers

Which characteristic does NOT belong to the basic vertebrate structure compared to amphioxus-like chordates?

Presence of flame cells Signup and view all the answers

Which of the following groups is included in the category of jawless fishes?

Lamprey Signup and view all the answers

What feature distinguishes Gnathostomata from other vertebrate groups?

Development of jaws Signup and view all the answers

Which group of fishes are known to include both living and extinct representatives?

Sarcopterygii Signup and view all the answers

What type of jaw suspension connects the palatoquadrate directly to the braincase and involves support from both the hyomandibular and chondrocranium?

Amphistylic Signup and view all the answers

Which type of jaw suspension is most commonly found in derived chondricthyans and bony fishes?

Hyostylic Signup and view all the answers

Which statement best describes the relationship of the visceral arches in jawless fishes compared to gnathostomes?

They are likely not homologous. Signup and view all the answers

What is characteristic of the pharyngeal basket of lampreys?

It is composed of fused cartilage. Signup and view all the answers

In which group is the palatoquadrate connected to the braincase directly and does not involve support from the hyomandibula?

Dipnoans Signup and view all the answers

What major component is NOT part of the postcranial skeleton?

Skull Signup and view all the answers

Which type of jaw suspension is characterized by the jaw being supported only by the hyomandibular?

Hyostylic Signup and view all the answers

What is the role of the opercular apparatus in bony fishes?

Protect gill structures Signup and view all the answers

What structure surrounds the spinal cord in precaudal vertebrae?

Neural Arch Signup and view all the answers

Which vertebral type is characterized by the presence of ribs?

Precaudal Vertebrae Signup and view all the answers

What characterizes a heterocercal tail?

Vertebral axis turns upward into a dorsal lobe Signup and view all the answers

Which part of the vertebrae is specifically associated with attaching ribs when present?

Parapophyses Signup and view all the answers

Which tail type features a hypural plate formed by the fusion of hypurals?

Homocercal tail Signup and view all the answers

What is the role of hypurals in modern fish tails?

Support main caudal fin rays Signup and view all the answers

Which statement accurately describes the caudal vertebrae?

They transition into the tail Signup and view all the answers

What is true about the neural spines in trunk vertebrae?

They always support the spinal cord Signup and view all the answers

Study Notes

Fish Evolution

Vertebrata includes all craniates; may or may not exclude Myxiniformes (hagfishes), which lack vertebrae.
Craniata encompasses all organisms with a chondrocranium, including Myxiniformes.
Gnathostomata excludes jawless fishes (Petromyzontiformes and Myxiniformes).
Osteichthyes includes all jawed fishes, excluding Chondrichthyes (sharks and rays).
Sarcopterygii refers to lobe-finned fishes, excluding Actinopterygii (ray-finned fishes).
Jawless fishes include living hagfish and lampreys, as well as extinct ostracoderms.

Origin of Jaws

Placoderms are the first vertebrates with true hinged jaws (extinct).
Chondrichthyes comprises living sharks, skates, rays, and chimaeras.
Acanthodii are an extinct group of fish noted for their spiny features.
Actinopterygii are categorized into basal groups (e.g., bichirs, sturgeons, gars) and derived teleosts.

Synapomorphies of Vertebrata

Key adaptations include predation, bone and cartilage structures, a developed head (including the brain), neural crest cells, a thyroid derived from endostyle, and specialized nephron structures instead of flame cells.
Segmentation (metamerism) is a characteristic feature of the vertebrate body plan, allowing evolutionary adaptations.

Fish Development

Gastrulation is crucial for embryo formation, impacting overall body structure.
Splanchnopleur is the tissue layer giving rise to the gut and involved in feeding, while somatopleur gives rise to body structures and is involved in locomotion and defense.
Evolutionarily, the ability to capture larger prey played a significant role in vertebrate emergence.

Skeletal Development

Living bony fishes possess two bone types: cartilage replacement (endochondral) bones and dermal bones.
The internal skeleton (e.g., ribs) is primarily composed of endochondral bone, while dermal bones provide armor or structural support.

Evolution of the Skull

Evolution shows a trend toward the fusion and reduction of bony elements from ancient actinopterygians to modern teleosts.
Hagfish exhibit a simple cranial structure, while lampreys lack dermal cranial components due to secondary loss.
Jaw suspension types include amphistylic, hyostylic, and autostylic, varying in structural support and evolutionary implications.

Branchial Complex

Structures associated with the gills and jaw function differ significantly between jawless fishes and gnathostomes in terms of element articulation and position.

Postcranial Skeleton

The vertebral column includes two sections: trunk (precaudal) vertebrae and caudal vertebrae.
Precaudal vertebrae feature neural arches, centra, and potential rib attachments, while caudal vertebrae have a focus on the tail structure.

Caudal Fin Types

Protocercal tail: an undifferentiated tail found in ancient fishes and some modern forms.
Heterocercal tail: characterized by an upward turn at the vertebral axis; typically seen in chondrichthyans and certain early actinopterygians.
Homocercal tail: features symmetrical fin rays with a fused spike-like structure (urostyle) at the end, commonly present in many modern bony fishes.

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Description

This quiz covers essential topics in Bio310 regarding fish anatomy, including the evolution of their skeletons, skin, and scales. Students will explore both extant and extinct species, focusing on the cranial and postcranial structures, fins, and scales. Prepare to test your knowledge on the fascinating world of fish evolutionary biology.