1. Cnidarians & Ctenophores (Cnidos) stinging nettle Ch
Cnidarians & Ctenophores (Cnidos) stinging nettle Ch.7 Marine Biology Book Ch.33-2 Biology Book
Mr. Werner - MATES

2. Phylum Cnidaria

3. Intro Video
Cnidarians
Biology of Cnidarians

4. Phylum Cnidaria
Includes marine organisms such as jellyfish, Portuguese man-of-war, coral, sea anemone, & sea fans
Hydra is a freshwater cnidarian

5. Phylum Cnidaria All carnivorous
Have 2 cell layers (epidermis -outer & gastrodermis-inner) with a hollow body called gastrovascular cavity
Contain a jelly-like layer between epidermis & gastrodermis called mesoglea
Single opening (mouth/anus) to gastrovascular cavity where food & water enter & wastes leave; called two-way digestive system
Have tentacles around mouth to pull in water & capture food

6. Cnidarians (Fig.7.8)
Have a simple nerve net to help with movement & senses
Medusae Have Statoctsts – control balance
Sessile members include corals, sea anemones, & sea fans
Have radial symmetry as adults
Contain stinging cells called cnidocytes in their tentacles that contain coiled stingers called nematocysts that can shoot out & paralyze prey

7. Stinging cell

9. Cnidarian Body Forms (Fig.7.6)
Have 2 basic body forms ---polyp & medusa
Polyp forms are usually sessile with upright tentacles arranged around the mouth at the top and with a thin layer of mesoglea
Corals, hydra, & sea anemones exist in the polyp form as adults

10. Cnidarians
Medusa forms are usually free- swimming, bell-shaped animals with tentacles that hang down
Jellyfish & Portuguese man-of-war are medusa form as adults
Polyps are the asexual stage
Medusa are the sexual stage

15. Cnidaria (Fig.7.7)
Hydra structure

19. JELLYFISH LIFE CYCLE

23. Moon Jelly Life Cycle Video

36. Coral Reefs
Most corals, like other cnidarians, contain a symbiotic algae called zooxanthellae, within their gastrodermal cells.
The coral provides the algae with a protected environment and the compounds necessary for photosynthesis.
Most importantly, they supply the coral with organic products of photosynthesis. These compounds, including glucose, glycerol, and amino acids, are utilized by the coral as building blocks in the manufacture of proteins, fats, and carbohydrates, as well as the synthesis of calcium carbonate (CaCO3).

37. Major coral reef sites are seen as red dots on this world map
Major coral reef sites are seen as red dots on this world map. Most of the reefs, with a few exceptions are found in tropical and semitropical waters, between 30° north and 30° south latitudes. (NOAA)

38. Types of Coral Reefs

39. Ctenophores Phylum Ctenophora
the name is pronounced with a silent "c", as "teen-o-four" or "ten-o-four"
comb jellies
eight rows of cilia arranged to form a stack of combs, also called comb plates, or ctenes ("comb bearer“).
Video 1 -
Video 2 – Blood-Belly Comb Jelly
Video 3 – BBC Coral Reef Danger
Video 3 – Arabian Sea

40. Ctenophores live only in marine waters 100-150 species
may be seasonally much more abundant in the spring and early summer
typically planktonic, transparent and unpigmented, and most swim by synchronous beating of the eight rows of comb plates

41. Coastal Ctenophores -3 groups
1. Cydippida -round or oblong in shape - Pleurobrachia
2. Lobata -have a pair of highly expandable lobes that are used as sticky prey capture surfaces
3. Most beroids are in this genus

42. Pleurobrachia

43. Bolinopsis infundibulum
Lobed Comb Jelly

44. Groups continued
Beroids are elongate animals that may be cylindrical or very flat, are often more translucent than transparent, and may be colorless or light pink or yellowish.
Beroes open up like a sack to engulf their prey, which is most typically other species of ctenophores

45. Beroe Comb Jelly

46. Oceanic ctenophores
defined by a combination of water temperature, light availability, depth and other factors
more fragile that coastal species & can break into a million pieces if touched

47. The ctenophore Deiopea is found near the surface around the world
The ctenophore Deiopea  is found near the surface around the world. Notice the thin filamentous branches of the tentacles which trail along the body from the mouth (top). (Approx length 5 cm).

48. This dramatic ctenophore lives near the bottom at depths around 1000 meters. It has not yet been named by scientists. Although it looks conspicuously colored when illuminated, there is practically no red light in its habitat, so red is as good as black. When disturbed, this species releases bioluminescent material into the water, causing a confusing swarm of sparkling lights. Notice also the darkly pigmented gut which masks the luminescence of its prey. (Length >15 cm)

49. Ctenophore light-scattering and bioluminescence
produced by beating of the eight rows of locomotory cilia
this is simple light diffraction or scattering of light by the moving cilia, not bioluminescence
Most (but not all) ctenophores are also bioluminescent, but that light (usually blue or green) can only be seen in darkness.

50. changing rainbow of colors running down the comb

51. Feeding
The tentacles of most cydippid and lobate ctenophores are covered by specialized microscopic sticky structures known as colloblasts
After prey capture, the tentacle with its adhering captured-prey is contracted and brought across the ctenophore's mouth for ingestion

52. Source for Comb Jellies