Corals Anemones Sea Fans and Jellyfish Aquatic Stinging

Corals, Anemones, Sea Fans, and Jellyfish Aquatic Stinging Nettles 6 -1

Chapter 6 Pages 6 -7 to 6 -8 Corals, Anemones, Sea Fans, and Jellyfish Characteristics of Phylum Cnidaria 6 -2

Members of Phylum Cnidaria • Phylum Cnidaria includes soft and hard corals, sea anemones, hydroids, sea fans, jelly fish, and siphonophores.

Characteristics of Phylum Cnidaria • Anatomical characteristics include: – They are radially symmetrical – symmetry around a central point. – They have a cup (polyp) or umbrella-shaped (medusa) body made of two layers of cells. Polyp - Attached Anemones and Corals Medusa - Free-Floating Jellyfish 6 -4

Characteristics of Phylum Cnidaria • Anatomical characteristics include: – Polyps can be solitary or colonial; medusa are freefloating – Mesoglea (jelly-like) separates the two tissue layers. – Tentacles line the rim of the polyp and medusa with a mouth-like opening in the middle. 6 -5

Characteristics of Phylum Cnidaria • Anatomical characteristics include: – They have a mouth that opens into the gastrovascular cavity (a space in the middle of their body used for digestion/reproduction). – They are structurally uncomplicated, with simple nerve net, muscle cells, and light receptors. – All share the ability to defend themselves with nematocysts. • These stinging structures are composed of special cells called cnidocytes. (You’ve seen better in video…) 6 -6

Special Attributes of Coral and Anemones • The largest class in phylum Cnidaria is class Anthozoa, the corals and anemones. Over 6, 000 species. – Members of this class are polyps that attach to the reef or other substrate. – Most coral and soft coral are colonial, anemones are individual organisms. Soft Coral Elkhorn Coral Stalked Anemone 6 -7

• Hard coral are the most ecologically significant thanks to the massive calcium carbonate reefs they build. – Coral colonies can grow for centuries and become so large that they shape coastlines and build entire islands. – Zooxanthellae live in the tissues of most species of hard coral, providing it food and helping eliminate waste through photosynthesis. Supercharged…. Plate Coral 6 -8

Special Attributes of Coral and Anemones • Zooxanthellae corals: – Live best in well-lit, clear water. – Actually thrive in low-nutrient, less productive areas. – Are sensitive to runoffs, fertilizers, etc. (can kill them) – Become colorless when stressed. This is called coral bleaching – a sign of a diseased and dying colony. Coral Bleaching 6 -9

• Soft coral and sea fans grow into tree-like structures built on protein skeletons. They are not reef builders. • Anemones have a mutualistic relationship with various species of anemonefish. – The fish receive protection by living in the anemone and the anemone receives food from the fish. Diver and Sea Fan Soft Coral 6 - 10

Special Attributes of Jellyfish • Jellyfish: – Are members of class Scyphozoa. – Range in size from smaller than a coin to more than 1 meter (3. 28 feet) across with tentacles more than 3 meters (9. 8 feet) long. – Are large planktonic organisms that swim, but also drift with the current. – Are weak swimmers that move by contracting and pulsating their rounded body, or bell. 6 - 11

• Jellyfish: – Feed on almost anything they catch with their tentacles. – Some species have very short tentacles and very mild stings, making them more of an annoyance than a threat to swimmers. Others have long tentacles and can sting severely. – Are eaten by some species of fish & turtles – Box jellyfish have a very potent Box Jellyfish toxin and can kill several adult humans. Box Jellyfish Stings 6 - 12

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Special Attributes of Fire Corals and Siphonophores • Fire coral: – Belong in the class Hydrozoa. – Colonial organism, looking much like hard corals. – Different from hard corals - forming more complex colonies and having complex lifecycles. Tentacles with Nematocysts – Life cycle alternates between polyp and medusa. – Most species can sting humans stings can be serious, hence their name. 6 - 14

• Siphonophores: – Belong in the class Hydrozoa. – Exist as planktonic colonies, yet within the colonies are specialized polyps adapted to feeding, reproduction, movement and other functions. – Can exceed 40 meters (131 feet) in length. – Can have powerful stings. – Are major predators. – Are a bridge between colonial animals and complex organisms. Diver with Planktonic Siphonophore 6 - 15

Special Attributes of Fire Corals and Siphonophores • The Portuguese Man-of-War is a siphonophore with a specialized buoyancy chamber to help it remain at the surface and tentacles underwater to catch prey. Float Tentacles with stinging, feeding, reproductive polyps 6 - 16

Comb Jellies - Gelatinous Carnivores 6 - 17

Comb Jellies - Gelatinous Carnivores • Characteristics of Phylum Ctenophora – Differences with jellyfish: • Ctenophores lack bag-like cnidarian body shape and stinging cells. – All are marine, living in many environments. – Have “comb rows” of cilia on bodies for movement. – Most are small - only a few millimeters or centimeters long. – Nearly colorless. 6 - 18

Comb Jellies - Gelatinous Carnivores • Characteristics of Phylum Ctenophora – Exhibit rainbow colored light produced by cilia. – Have organized tissues but lack true organs. – Has a nerve net and reproduces sexually. – Are carnivorous - eating small plankton. 6 - 19