29.1 Section Objectives – page 763

1. 29.1 Section Objectives – page 763 Section Objectives: 29.1 • Compare similarities and differences among the classes of echinoderms. • Interpret the evidence biologists have for determining that echinoderms are close relatives of chordates.

2. Section 29.1 Summary – pages 763-769 • _________ move by means of hundreds of hydraulic, suction-cup-tipped appendages and have skin covered with tiny, jawlike pincers. • Echinodermsare found in all the _____ of the world.

3. Section 29.1 Summary – pages 763-769 • If you were to examine the skin of several different echinoderms, you would find that they all have a hard, _____, or bumpy endoskeleton covered by a thin ________.

4. Section 29.1 Summary – pages 763-769 • ___ ___, sometimes called starfishes, may not appear spiny at first glance, but a close look reveals that their long, tapering arms, called ___, are covered with short, rounded spines.

5. Section 29.1 Summary – pages 763-769 • Some of the spines found on sea stars and ___ _____ have become modified into pincer-like appendages called _________ (PEH dih sih LAHR ee ay).

6. Section 29.1 Summary – pages 763-769 Pedicellariae • An echinoderm uses its jaw-like _______ for protection and for cleaning the surface of its body.

7. Section 29.1 Summary – pages 763-769 • You may remember that ____________is an advantage to animals that are stationary or move slowly. • Radial symmetry enables these animals to sense potential food, predators, and other aspects of their environment from all directions.

8. Section 29.1 Summary – pages 763-769 • The water vascular system is a _____ system that operates under water pressure. • Water enters and leaves the water vascular system of a sea star through the _______ (mah druh POHR ite), a sieve-like, disk-shaped opening on the upper surface of the echinoderm’s body.

9. Section 29.1 Summary – pages 763-769 • The underside of a sea star has ____ feet that run along a groove on the underside of each ray.

10. Section 29.1 Summary – pages 763-769 • Tube feet are hollow, thin-walled tubes that end in a ______ cup. • Tube feet look somewhat like miniature droppers. • The round, muscular structure called the ______ (AM pew lah) works something like the bulb of a dropper.

11. Section 29.1 Summary – pages 763-769 • Each ____ foot works independently of the others, and the animal moves along slowly by alternately pushing out and pulling in its tube feet. Ampullae

12. Section 29.1 Summary – pages 763-769 • Tube feet also function in gas exchange and excretion. Gases are exchanged and wastes are eliminated by ________ through the thin walls of the tube feet.

13. Section 29.1 Summary – pages 763-769 • All echinoderms have a mouth, stomach, and intestines, but their methods of obtaining food vary. • Sea stars are _________ and prey on worms or on mollusks such as clams.

14. Section 29.1 Summary – pages 763-769 • Most sea urchins are ___________ and graze on algae. • ______ stars, ___ lilies, and sea _______ feed on dead and decaying matter that drifts down to the ocean floor.

15. Section 29.1 Summary – pages 763-769 • Echinoderms have no head or brain, but they do have a ____ ____ ____ that surrounds the mouth. Ring canal

16. Section 29.1 Summary – pages 763-769 • Nerves extend from the _____ ____down each ray. • Each ______ nerve then branches into a nerve net that provides sensory information to the animal.

17. Section 29.1 Summary – pages 763-769 • ___ ____are an exception. A sea star’s body consists of long, tapering rays that extend from the animal’s central disk. • A sensory organ known as an ______ and consisting of a cluster of light-detecting cells is located at the tip of each arm, on the underside.

18. Section 29.1 Summary – pages 763-769 • _______ enable sea stars to detect the intensity of light. • Sea stars also have chemical ______ on their tube feet.

19. Section 29.1 Summary – pages 763-769 • If you examine the larval stages of echinoderms, you will find that they have ___________ ______. • Through __________, the free-swimming larvae make dramatic changes in both body parts and in symmetry.

20. Section 29.1 Summary – pages 763-769 • Echinoderms are deuterostomes. • This pattern of development indicates a close relationship to ______, which are also deuterostomes.

21. Section 29.1 Summary – pages 763-769 • Approximately 6000 species of echinoderms exist today. • About one-fourth of these species are in the class _______ (AS tuh ROY dee uh), to which the sea stars belong.

22. Section 29.1 Summary – pages 763-769 • The five other classes of living echinodems are Ophiuroidea (OH fee uh ROY dee uh), the brittle stars; Echinoidea (eh kihn OY dee uh), the sea urchins and sand dollars.

23. Section 29.1 Summary – pages 763-769 • Holothuroidea (HOH loh thuh ROY dee uh), the sea cucumbers; Crinoidea (cry NOY dee uh), the sea lilies and feather stars; and Concentricycloidea (kon sen tri sy CLOY dee uh), the sea daisies. Sea Cucumber

24. Section 29.1 Summary – pages 763-769 • Most species of sea stars have ____ rays, but some have more. Some species may have more than 40 rays.

25. Section 29.1 Summary – pages 763-769 • Brittle stars are extremely ______. • This adaptation helps the brittle star survive an attack by a predator. • While the predator is busy with the broken off ray, the brittle star can escape. A new ray will ________.

26. Section 29.1 Summary – pages 763-769 • Brittle stars propel themselves with the snake like, slithering motion of their flexible rays. • They use their tube feet to pass particles of food along the rays and into the mouth in the ____ ____.

27. Section 29.1 Summary – pages 763-769 • Sea urchins and sand dollars are _____ or disk-shaped animals covered with spines; they do not have rays. • A living sand dollar is covered with minute, hair-like spines that are lost when the animal dies. • A sand dollar has tube feet that protrude from the petal-like markings on its upper surface.

28. Section 29.1 Summary – pages 763-769 • These tube feet are modified into ____ and are used for respiration. • Tube feet on the animal’s bottom surface aid in bringing food particles to the mouth.

29. Section 29.1 Summary – pages 763-769 • Sea urchins look like living pincushions, bristling with long, usually pointed spines. • Sea urchins have long, slender tube feet that, along with the spines, aid the animal in ________.

30. Section 29.1 Summary – pages 763-769 • Sea cucumbers are so called because of their vegetable-like appearance. • Their leathery covering allows them flexibility as they move along the ocean floor.

31. Section 29.1 Summary – pages 763-769 • When sea cucumbers are threatened, they may expel a tangled, sticky mass of tubes through the anus, or they may rupture, releasing some internal organs that are _______ in a few weeks. • Sea cucumbers reproduce by shedding ____ and _____ into the water, where fertilization occurs.

32. Section 29.1 Summary – pages 763-769 • Sea lilies and feather stars resemble plants in some ways. • Sea lilies are the only ______ echinoderms. • Feather stars are sessile only in _____form. The adult feather star uses its feathery arms to swim from place to place.

33. Section 29.1 Summary – pages 763-769 • Sea daisies are flat, disk-shaped animals less than 1 cm in diameter. • Their tube feet are located around the edge of the disk rather than along radial lines, as in other echinoderms.

34. Section 29.1 Summary – pages 763-769 • The earliest echinoderms may have been bilaterally symmetrical as adults, and probably were attached to the ocean floor by _______. • Another view of the earliest echinoderms is that they were bilateral and ____ swimming.

35. Section 29.1 Summary – pages 763-769 • The echinoderms represent the only major group of deuterostome ___________. • This pattern of development is one piece of evidence biologists have for placing echinoderms as the closest invertebrate relatives of the ________.

36. Section 29.1 Summary – pages 763-769 • Most echinoderms have been found as fossils from the early Paleozoic Era. • Fossils of brittle stars are found beginning at a later period. Not much is known about the origin of sea daisies.

37. 29.2 Section Objectives – page 770 Section Objectives: 29.2 • Summarize the characteristics of chordates. • Explain how invertebrate chordates are related to vertebrates. • Distinguish between sea squirts and lancelets.

38. Section 29.2 Summary – pages 770-775 • The phylum _________includes three subphyla: Urochordata, the ________ (sea squirts); Cephalochordata, the ______; and Vertebrata, the vertebrates. • Invertebrate chordates have a ______, a dorsal hollow nerve cord, ______pouches, and a ______ tail at some time during their development.

39. Section 29.2 Summary – pages 770-775 • In addition, all chordates have ______ symmetry, a well-developed ______, and segmentation. Notochord Dorsal hollow nerve cord Anus Pharyngeal pouches Mouth Muscle blocks Postanal tail

40. Section 29.2 Summary – pages 770-775 • The embryos of all chordates have a _____ (NOH tuh kord) — a long, semirigid, rod-like structure located between the digestive system and the dorsal hollow nerve cord. Nerve cord Gill slits Notochord

41. Section 29.2 Summary – pages 770-775 • In invertebrate chordates, the notochord may be retained into adulthood. But in vertebrate chordates, this structure is replaced by a _______. • ________ chordates do not develop a backbone.

42. Section 29.2 Summary – pages 770-775 • The pharyngeal pouches of a chordate embryo are paired openings located in the _______, behind the mouth. • In aquatic chordates, pharyngeal pouches develop openings called _____ ____. • In terrestrial chordates, pharyngeal pouches develop into other structures.

43. At some point in development, all chordates have a _____ tail. Section 29.2 Summary – pages 770-775 • Humans are chordates, and during the early development of the human _____, there is a postanal tail that disappears as development continues. Postanal tail

44. Section 29.2 Summary – pages 770-775 • In most animals that have tails, the digestive system extends to the tip of the tail, where the ____ is located. • _______, however, usually have a tail that extends beyond the anus.

45. Section 29.2 Summary – pages 770-775 • Muscle _____ aid in movement of the tail. • Muscle blocks are modified body segments that consist of _______ muscle layers. • Muscle blocks are anchored by the notochord, which gives the muscles a firm structure to pull against.

46. Section 29.2 Summary – pages 770-775 • _______ genes specify body organization and direct the development of tissues and organs in an embryo. • Studies of chordate homeotic genes have helped scientists understand the process of development and the relationship of invertebrate chordates to vertebrate chordates.

47. Section 29.2 Summary – pages 770-775 • The invertebrate chordates belong to two subphyla of the phylum chordata: subphylum Urochordata, the tunicates (TEW nuh kaytz), also called sea squirts, and subphylum Cephalochordata, the lancelets.

48. Section 29.2 Summary – pages 770-775 • Although adult tunicates do not appear to have any shared chordate features, the _____ stage, has a tail that makes it look similar to a tadpole.

49. Section 29.2 Summary – pages 770-775 • Tunicate larvae do not ___and are free swimming after hatching. • They soon settle and attach themselves with a sucker to boats, rocks, and the ocean bottom. • Many adult tunicates secrete a ____, a tough sac made of _______, around their bodies.

50. Section 29.2 Summary – pages 770-775 • Colonies of tunicates sometimes secrete just one big tunic that has a common opening to the outside. • Only the ______ ____in adult tunicates indicate their chordate relationship.