Chordata Characteristics and Cephalochordata

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Questions and Answers

Which feature is NOT characteristic of organisms in Phylum Chordata?

Notochord at some life stage

Closed circulatory system

Ventral nerve cord (correct)

Dorsal hollow nerve cord

What structure in higher Chordata develops from the notochord?

Visceral clefts

Endoskeleton

Dorsal nerve cord

Vertebral column (correct)

Which of the following is true about the circulatory system of most chordates?

It is closed with a heart (correct)

It is open and involves sinuses

It varies widely among species

It lacks a heart

What is the function of the endostyle in Tunicata?

To capture food particles Signup and view all the answers

Which statement accurately describes visceral clefts in Chordata?

They occur as perforations during embryonic development. Signup and view all the answers

Which class of Chordata is characterized by living in marine environments, often in colonies?

Urochordata Signup and view all the answers

What is a defining feature of the digestive system in Tunicata?

Presence of a distinct stomach and intestines Signup and view all the answers

Which of the following statements about the notochord is true?

It provides support and may be lost in some adult forms. Signup and view all the answers

Which characteristic is unique to adult Appendicularia compared to other classes in Tunicata?

Retains a notochord throughout life Signup and view all the answers

What is the primary function of nephrocytes in the excretory system of Tunicata?

Excretion of waste Signup and view all the answers

Which of the following statements about Cephalochordates is incorrect?

They are part of the subphylum Vertebrate. Signup and view all the answers

Which class of Tunicata is characterized by its sessile, filter-feeding lifestyle?

Ascidiacea Signup and view all the answers

Which feature do larvae of Tunicata have that adults lack?

Postanal tail Signup and view all the answers

What is a common characteristic of all classes within the Tunicata?

They possess a notochord at some stage. Signup and view all the answers

Which term best describes the habitat of Thaliacea?

Pelagic Signup and view all the answers

Comparatively, how do the reproductive systems of Tunicata classes differ from those of vertebrates?

Tunicates are hermaphrodites. Signup and view all the answers

What characteristic distinguishes lancelet larvae from adult lancelets?

Lancelet larvae are asymmetrical and simpler in structure. Signup and view all the answers

Which feature of segmentation is stated to enhance locomotion in lancelets?

It provides more effective body coordination. Signup and view all the answers

What type of habitat do lancelets prefer?

Soft bottoms, including various types of sand and gravel. Signup and view all the answers

What is the primary body cavity present in lancelets called?

Enteron Signup and view all the answers

Which descriptor accurately reflects the fins of lancelets?

They are equipped with dorsal, caudal, and ventral odd fins. Signup and view all the answers

How is the coelom developed in lancelets during embryonic development?

As outpouchings in the gut of the embryo. Signup and view all the answers

What general behavior do lancelets exhibit in their natural environment?

They seek proper habitat and escape from predators. Signup and view all the answers

What does the segmentation in the bodies of lancelets include?

Blocks of muscles and related nerve supplies. Signup and view all the answers

What is the significance of lancelets in evolutionary studies?

They serve as a model for understanding vertebrate characteristics. Signup and view all the answers

Which of the following accurately describes the digestive system of lancelets?

They utilize an endostyle for trapping food. Signup and view all the answers

How do lancelets excrete waste products?

Through the anus and atriopore. Signup and view all the answers

What characteristic of lancelets indicates their classification as chordates?

Presence of a dorsal hollow nerve cord. Signup and view all the answers

Which statement about the reproductive system of lancelets is correct?

They exhibit external fertilization with separate sexes. Signup and view all the answers

Which feature limits the ecological role of lancelets in nutrition?

They are not abundant enough to be significant in the food chain. Signup and view all the answers

What is true regarding the pharyngeal structure of lancelets?

It plays a role in both feeding and respiration. Signup and view all the answers

Which of the following best describes the circulatory system of lancelets?

It is a closed system with a simple heart. Signup and view all the answers

Study Notes

Phylum Chordata: Characteristics

Bilaterally symmetrical
Triploblastic, coelomate
Metamerically segmented
Deuterostomia
Notochord: A slender, stiff, flexible rod running along the back at some life stage, developing into a vertebral column in higher chordates.
Dorsal hollow nerve cord: Unlike protostomes, which have a ventral nerve cord.
Pharyngeal slits: Perforations on each side of the pharynx present in all chordate embryos. They may develop into gills in some species and are reduced or lost in later adult stages.
Postanal tail: Present in some stage of the life cycle, may be reduced or lost in adult forms.

Chordate Subphylum: Cephalochordata

Small, fish-like marine invertebrates
Close relatives of vertebrates.
Notochord, dorsal hollow nerve cord, pharyngeal gill slits, postanal tail present throughout life.
About 20 species in two families (with one genus) (e.g. Branchiostoma).
Fossil record dates back to the early Cambrian period (around 525 million years ago.)
Adults approximately 6 to 7 centimeters in length.

Chordate Subphylum: Urochordata (Tunicata)

3,000 species.
Numerous gill slits on pharynx for suspension feeding.
Notochord and nerve cord in larval stages only
Adult body has a polysaccharide tunic (secreted coating).
Three classes: Ascidiacea (ascidians), which are benthic, often colonial; Thaliacea (salps), pelagic, colonial; and Appendicularia (larvaceans), pelagic, solitary.
Adults often retain larval characteristics

General Features of Chordates

Digestive System: Mouth, pharynx with gill slits, intestines, and anus. They can be filter feeders.
Breathing System: Pharynx with gill slits, atrium, atriopore.
Circulatory System: Closed system with a simple heart in most cases.
Excretory System: Nephrocytes and excretion through the atrial siphon or anus.
Nervous System: Dorsal hollow nerve cord, but central nervous system isn't a visible brain in some.
Reproductive System: Mostly separate sexes, external fertilization, and larval development phases similar to those of vertebrates and tunicates are possible.

Chordate Ecology, Importance, and Movement

Ecology: Inhabit soft bottoms of shallow, coastal waters.
Importance: Provides information about evolutionary transition from invertebrates, to vertebrates.
Movement: Lancelets can swim forward and backwards quickly; have segmented muscles and fins for movement.
Segmentation: Body segmentation (metamerism) extends to body cavities, nerves, and excretory structures, which contributes to overall body coordination.

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Description

Explore the fascinating features of Phylum Chordata, including their unique anatomical structures like the notochord and dorsal hollow nerve cord. Additionally, dive into the subphylum Cephalochordata and learn about these small, fish-like marine invertebrates that share a close relationship with vertebrates. Test your knowledge with this informative quiz!