chordata

Q: How many species are in Phylum Chordata?

A: Approximately 56,000 species

Q: What type of development do chordates have?

A: Deuterostome development

Q: Do chordates have a coelom?

A: Yes, chordates are coelomates (have a true body cavity)Q: What are the nearest relatives of chordates?

Q: What are the nearest relatives of chordates?

A: Echinoderms

Q: What do chordates and echinoderms have in common?

A: Both are deuterostomes (the only two deuterostome phyla)

Q: What are the only two deuterostome phyla?

A: Chordata and Echinodermata

Q: Are chordates more closely related to echinoderms or arthropods?

A: Echinoderms (both are deuterostomes, while arthropods are protostomes)

Q: What does it mean that chordates are deuterostome coelomates?

A: They have deuterostome development (blastopore becomes anus) and a true body cavity (coelom)

Q: Do all chordates have all four defining characteristics throughout their entire lives?

A: No, all chordates have all four characteristics at some time in their lives (often during embryonic development), but may lose some as adults

Q: Give an example of a chordate that has all four characteristics only during development.

A: Humans (we have pharyngeal slits, notochord, and postanal tail as embryos, but these are reduced or modified in adults)

Q: What are somites?

A: Segmented blocks of tissue that develop along the body during embryonic development (form muscles, vertebrae, and other structures)

Q: What is another distinguishing characteristic of chordates (besides the four main ones)?

A: Somites (segmented body blocks during development)

Q: What type of skeleton do chordates have?

A: Internal skeleton (endoskeleton)

Q: How do chordate muscles work with the skeleton?

A: Muscles work against the internal skeleton (endoskeleton provides support and attachment points for muscles)

Q: What are two additional characteristics that distinguish chordates?

A: 1) Somites (segmented body blocks), 2) Internal skeleton against which muscles work

Q: What is the difference between the skeleton in chordates vs. arthropods?

A: Chordates have an internal skeleton (endoskeleton); arthropods have an external skeleton (exoskeleton)

Q: What structures develop from somites?

A: Muscles, vertebrae (backbone segments), and other segmented body structures

Q: How many subphyla is Phylum Chordata divided into?

A: Three subphyla

Q: What are the three subphyla of Phylum Chordata?

A: 1) Urochordata (sea squirts), 2) Cephalochordata (lancelets), 3) Vertebrata

Q: What is Subphylum Urochordata?

A: Sea squirts (tunicates)

Q: What is Subphylum Cephalochordata?

A: Lancelets (also called amphioxus)

Q: What is Subphylum Vertebrata?

A: Vertebrates (animals with backbones/vertebrae)

Q: Which two chordate subphyla are nonvertebrates?

A: Urochordata (sea squirts) and Cephalochordata (lancelets)

Q: What does "nonvertebrate" mean?

A: No vertebrae or bones (lacking a backbone)

Q: Do urochordates and cephalochordates have vertebrae?

A: No, they are nonvertebrate chordates (no vertebrae or bones)

Q: What do sea squirts and lancelets have in common?

A: Both are nonvertebrate chordates (have chordate features but lack vertebrae/bones)

Q: Which chordate subphylum includes animals with backbones?

A: Subphylum Vertebrata

Q: How many species are in Subphylum Urochordata?

A: Approximately 1,250 species

Q: What is another name for urochordates?

A: Tunicates (also called sea squirts)

Q: What is the habitat of tunicates?

A: Marine animals (ocean/saltwater)

Q: What do tunicate larvae look like?

A: Tadpole-like

Q: Do tunicate larvae exhibit all four chordate characteristics?

A: Yes, larvae exhibit all four chordate characteristics

Q: Are tunicate larvae free-swimming or sessile?

A: Free-swimming

Q: Do tunicate larvae feed?

A: No, larvae are free-swimming but do not feed

Q: What happens to tunicate larvae after a few days?

A: They settle and transform (metamorphose) into adults

Q: What is the lifestyle of adult tunicates?

A: Immobile filter-feeders (sessile)

Q: What chordate features do adult tunicates lose during metamorphosis?

A: Tail, nerve cord, and notochord

Q: Do adult tunicates have a major body cavity or segmentation?

A: No, they have no major body cavity or segmentation

Q: What is a tunic?

A: A cellulose sac secreted by the tunicate that surrounds the animal

Q: What material is the tunic made of?

A: Cellulose

Q: Why are urochordates called "tunicates"?

A: Because they secrete a tunic (cellulose sac) that surrounds the animal

Q: Describe the complete life cycle transformation in tunicates.

A: Tadpole-like larvae (free-swimming, all 4 chordate features, don't feed) → settle after a few days → transform into immobile filter-feeding adults (lose tail, nerve cord, notochord)

Q: When do tunicates display all four chordate characteristics?

A: During the larval stage (adults lose most chordate features)

Q: What is unusual about tunicate tunics?

A: They are made of cellulose, which is rare in animals (usually found in plants)

Q: How many species are in Subphylum Cephalochordata?

A: Approximately 30 species

Q: What is another name for cephalochordates?

A: Lancelets (also called amphioxus)

Q: What is the habitat of lancelets?

A: Marine (ocean/saltwater)

Q: Do lancelets have scales?

A: No, lancelets are scaleless

Q: Does the notochord persist throughout a lancelet's life?

A: Yes, the notochord persists throughout the animal's entire life

Q: What do lancelets feed on?

A: Plankton

Q: How do lancelets feed?

A: Using cilia-generated currents to filter plankton from water

Q: What type of feeding do lancelets use?

A: Filter feeding (using cilia to create water currents)

Q: Are cephalochordates considered the closest relatives to vertebrates?

A: Possibly - they may be the closest relatives to vertebrates (this is still debated)

Q: What is a key difference between urochordates and cephalochordates regarding the notochord?

A: Urochordates lose the notochord as adults; cephalochordates keep the notochord throughout life

Q: What are the key characteristics of lancelets?

A: Scaleless, marine, notochord persists throughout life, no distinguishable head, filter-feed on plankton using cilia