1. Marine Invertebrates (other than corals): 3-30-10 Some nice, some not so.

2. Sea Walnut, Beroe sp.

3. Comb Jelly, Mnemiopsis sp. – a main source of tropical bioluminescence

4. Mnemiopsis showing its bioluminescence.

5. SPEAKING OF BIOLUMINESCENCE: WHAT IS IT? • It is light produced in a living organism. • It occurs in many different life forms. • In all life forms, the light is produced in the same way: • Oxygen + luciferin are catalyzed by the enzyme luciferase • Oxyluciferin and light are produced • This is a very efficient form of light production, with no energy lost due to heat production

6. WHAT ARE THE STAR-LIKE SPECKS FLASHING IN SALT WATER? • These small flashes are usually caused by a microscopic dinoflagellate, Noctiluca.

7. WHY DOES NOCTILUCA BIOLUMINESCE? • The basic answer is: agitation • Anything that goes bump-in-the-night: a fish swims by, someone stirs the water with a stick, a diver plunges in, a boat propeller churns along (sometimes leaving a green light trail in its wake), etc. Noctiluca washed up on a sandy beach twinkle as one walks by. • A common interaction: • A predatory copepod approaches the Noctiluca. • The Noctiluca flashes • The copepod is confused and distracted • The Noctiluca escapes • A nearby fish understands what is happening and zips in and consumes the copepod (sometimes the Noctiluca is also consumed)

8. Have you ever seen a bioluminescent angel? (from Spalding 2004, p. 148) Obviously he’s waving his arms in water with lots of bioluminescent organisms.

9. WHAT IS FLUORESCENCE? • Fluorescence occurs when the chemistry or structure of something causes light to be given off from a surface that is exposed to another form of light. • This occurs when the wave length of the reflecting light is longer than the impinging light. • We are most aware of fluorescencing signs and posters. • “Brightening” detergents contain substances that cause fluorescence, thus making clothes appear “whiter” to the eye. • If fluorescence is occurring, the glow disappears immediately when the light source is turned off.

10. WHAT IS PHOSPHORESCENCE? • Phosphorescence occurs when the chemistry or structure of a surface glows (same wave-length change as discussed for florescence), but it gradually fades over time after the light source is turned off.

11. Bioluminescence, in contrast, results from the internal luciferin-oxygen-luciferase reaction. It is not reflection.

12. HOW DO JELLYFISH & HYDROIDS STING?

13. Nematocysts are the stinging organs of jellyfish and their relatives. They are spring-loaded, and inject a venom loaded barb in the target. From Jan A. Pechenik, Biol. Of Invertebrates, p. 79.

14. Hydroids are relatively small, but can give you a good sting.

15. Moon Jelly, Aurelia – not harmful to humans.

16. Cabbagehead Jellyfish – Normally associate in schools, but rarely as abundant as the view below in the harbor in Trinidad.

17. Box Jellyfish (aka Marine Stinger or Sea Wasp), Chironex fleckeri - Northern Australia’s deadly visitor. They are along the Australian coast north of the Tropic of Capricorn between October & May.

18. This beautiful animal can . . . From National Geographic.

19. . . . cause severe reactions, if not death. One box jelly has enough venom to kill 60 humans. People have died in just 4 minutes. From National Geographic

20. Yet another bioluminescent jelly.

21. Be wary of these “plastic bags.” It is the floatation portion of a Portuguese Man-of-War, Physalia. It is accompanied by long tentacles, sometimes invisible in the sand around the float, that can sting horribly.

22. How do Portuguese Man-of-War move? • They have a “sail” on top of the float. • The sail is positioned so that the critter moves at 45º off the wind (the same way sailors set their sails). • About half are slanted opposite the others, thus insuring that not all will be blown up on beaches at the same time.

23. Is the Portuguese Man-of-War a simple jellyfish? • It is a floating complex of many individual living things. • There are a number of polyp-like critters. • There are many medusa-like individuals. • They all work together to make an eating machine that can be very dangerous to humans.

24. Structure of a Portuguese Man-of-war.

25. Small fish are commonly seen swimming about among the tentacles. • All are immune to the venom. • 50 or more species of fish are known to spend at least some time living among the tentacles of jellyfish. • Most are juveniles, and they leave as they grow. • Some are specialized enough to always live in jellyfish tentacles.

26. Sea Nettle, Chrysosora, is one of the most common jellies in the Caribbean.

27. Upside-down Jellyfish, bottom at the margin of mangrove

29. Brittle stars can be very abundant.

30. Brittle stars are often found clinging to sponges and corals underwater along walls.

31. Some sea stars can be locally abundant, and we typically see them when snorkeling in the mangroves of Turneffe Atoll.

32. Sea stars and their relatives move about by means of a water vascular system that very efficiently uses water pressure.

33. Steer clear of Sea Urchins, but enjoy their beauty.

34. The long-spined urchin can be quite common in the Caribbean.

35. Sand Dollars are related to sea stars. Though delicate, they are architecturally sound.

36. Sea biscuits, a relative of sand dollars, from the Philippines.

37. A relative of sea star is the sea cucumber. This specimen is a Donkey Dung Sea Cucumber (duh, how’d it get its name?). Dorsal view. Ventral view.

38. Katie Greely and her new friend.

39. The Tigertail is a sea cucumber that sticks out from under corals on the sea floor after dusk.

40. Feather Worms, Spirobranchus giganteus (on brain coral) – Australia. There are many in Belize.

41. Christmas Tree Worm – Belize Photo by Tony Rath.

42. Feather Duster Worm on brown coral

43. Polychaete worms (this is a Bearded Fireworm) are usually abundant in marine situations, especially in estuaries and grassbeds.

44. Fireworms are polychaete worms that sting when touched. Be aware of any “worm” with fuzzy, hairy areas.

45. Bioluminescent benthic “glow worm” polychaetes, Odontosyllis luminosa (Syllidae). • First noted by Christopher Columbus in November, 1492, but the species was described in 1990. • Happens for about 15 minutes per evening, around 7 pm, for just a few days after a full moon. • Gravid females, about 20 mm long, swim to the surface from the bottom with their eggs and associated bioluminescent materials. • The also bioluminescent males, about 12 mm long, follow them. • If males are very near them, the females’ gonopores spew their glowing load with eggs at the surface, and the eggs are fertilized externally by the males. If no males approach a female, she releases bioluminescent material, but no eggs. • The females presumably live to mate again, after sinking back to the bottom and forming mucous tubes.

46. Sponges come in three types, based on their anatomy and how water flows through them.

47. A more anatomic model:

48. The sponge itself is not a single living organism. It is a colonial organism made of spongin, spicules, and choanocytes that line the channels and cavities and move the water (by flapping their flagella) and feed on the food that is thus moved through. The choanocytes are the living elements of the sponge.

49. Sponges maintain their shape with the help of supportive spongin (L) and/or glass-like spicules.

50. The Hawksbill Sea Turtle, Eretmochelys imbricata, feeds almost exclusively on sponges. They are able to tolerate having large balls of needle-like spicules in their stomachs.