Learning Goal Describe the main characteristics of cnidarians

Learning Goal: �Describe the main characteristics of cnidarians �Explain why coral reefs are important Warm up: What makes up a coral reef? Homework: � Finish all questions on packet � TEST on Wednesday on Ch. 9 MONDAY 2/29/16 pages 6, 7, 8, & 9 Sec 1 & 3

Cnidarians Chapter 9 Section 3

�Jellyfish, corals, and sea anemones �Invertebrates that have stinging cells to capture food and protect themselves �Take food into central body cavity Cnidarians

�Two different body plans (vase and bowl) �Radial symmetry �Central hollow cavity �Tentacles containing stinging cells Cnidarians: Body Structure

�Radial symmetry - symmetry around a central axis, as in a starfish

�Vase-shaped body plan is a POLYP �Sea anemone �Mouth opens at top �Tentacles spread out from around mouth �Most are attached to underwater surface Body Structure: Polyp

�Bowl-shaped body plan is a MEDUSA �Jellyfish �Adapted for a swimming life �Mouths open downward and tentacles trail down Body Structure: Medusa

�Use stinging cells to catch animals they eat (prey) �Contains threadlike structure with spines �Uses tentacles to pull prey to mouth �Takes food into central body cavity �Expels undigested food through mouth Obtaining Food

�Unlike adult sponges, many cnidarians move to escape danger and to obtain food �Jellyfish ◦ Swim through the water ◦ Hydras turn slow somersaults �Sea Anemones ◦ Stretch out, shrink down, bend slowly from side to side Movement

�Asexual Reproduction ◦ Hydras, corals, and sea anemones �Sexual Reproduction ◦ Jellyfish Reproduction

�Colony ◦ a group of many individual animals �Stony corals and Portuguese man-ofwar Life in a Colony

�a coral reef is built by cnidarians �coral reefs are home to more species of fishes and invertebrates than any other environment on Earth �Coral polyps produce hard, stony skeletons around their soft bodies Stony Coral

�Contains as many as 1, 000 individuals that function together as one unit �Top: gas filled chamber, allows colony to float �Bottom: polyps with different functions drift below ◦ Some catch prey and help with digestion and reproduction Portuguese Man-of-War