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Waikiki Aquarium Worksheet
Focus of Visit
This worksheet is designed to focus your attention on marine invertebrates (e.g., crabs, lobster, sea urchins, starfish) and vertebrates (e.g., fishes, sharks, monk seals) maintained by the Waikiki Aquarium. The Aquarium’s exhibits are largely structured around the habitats in which a diversity of organisms exists. I encourage you to appreciate how an animal’s anatomy and life history enable it to survive in the suite of physical and biological features that characterize its environment.
Corals Are Alive: Display 4
To the right as you enter are a series of displays comprising the Corals Are Alive exhibit. Corals belong to the phylum Cnidaria, as do hydras, jellyfish, and sea anemones. Cnidarians are diploblastic (lacking mesoderm) and have radial symmetry, suggesting their early evolutionary history.
The basic body plan of all cnidarians is a sac with a central digestive compartment, the gastrovascular cavity. The single opening to this cavity operates as both mouth and anus. This basic body plan has two variations: the sessile (attached) polyp and the floating medusa. Some cnidarians exist only as polyps, others only as medusas, and others include both the polyp and medusa phase in their life cycle. This dimorphic life history is a unique characteristic of the phylum Cnidaria.
Within the phylum Cnidaria, corals belong to the class Anthozoa, along with sea anemones and sea fans. Anthozoans occur as either solitary or colonial polyps, in which the medusa stage is completely absent. Stony, or hard, corals produce an external skeleton of calcium carbonate. Some corals are solitary (single polyps), but the majorities are colonial, composed of many generations of polyps interconnected through their soft tissues. Examine the displays to answer the following questions:
Display 4:
1. What are 5 general growth forms displayed by coral skeletons?
2a. What is the skeletal growth rate of a fast-growing species of coral?
b. A slow-growing species?
3. What are 4 destructive human endeavors from which corals and reefs need protection?
4. Soft corals are classified as ahermatypic. What is their primary mode of nutrition?
Display 5:
5. Which species would you find in rough surge?
Display 9:
6. Where in the coral polyp are the zooxanthellae located?
Tank 14:
Mangrove Forest
Mangrove forests are a community of unrelated plants living in areas that are inundated by tides. They are dominated by one or several species of mangroves, of which more than 30 species exist worldwide. Despite belonging to many different families, mangrove species have come up with surprisingly similar solutions to the problems of surviving in water-logged, unstable, and oxygen-deficient soils.
How do mangroves manage to flourish in such a saline environment? The first line of defense for many species, such as the Rhizophora sp. in this tank, is to stop much of the salt from entering at all by filtering it out at root level. Secondly, some species quickly excrete salt that has entered the system, primarily by way of special salt glands in the leaves. A third method is to concentrate salt in the bark or older leaves, which carry it with them when they drop. A number of other features additionally serve to conserve water. These include a thick, waxy cuticle or dense trichomes (hairs) on the leaves to reduce transpiration. The stomata (openings) are often sunken below the leaf surface, where they are protected from drying winds. Leaves are also commonly succulent, storing water in fleshy internal tissue.
In unstable soil an extensive root system is necessary simply to keep the mangrove trees upright. Most mangroves have more living matter below the ground than above it. The main mass of roots, however, is generally within the top 2 meters, rather than extending into deeper, oxygen-deficient soil. Even in this shallow soil little oxygen is available; consequently, many mangrove species have part of their root system raised above the mud. These roots are covered with special breathing cells, called lenticels, which draw in air; they are connected to spongy tissue within the roots. The red mangrove (Rhizophora sp.) seen here is commonly found close to the seaward side of mangrove forests and is therefore subjected to high wave energy. It has developed a particularly strong system of prop roots, which provide numerous anchors for the tree as well as a large surface area for oxygen-absorbing lenticels.
7. Although they are often cleared for development and are not native to Hawaii, what are 3 benefits provided by mangrove forests that would argue against destroying them?
Seagrass Beds (Tank 14)
A seagrass is an angiosperm (flowering plant), complete with leaves, an underground stem (rhizome), and a root system. Seagrasses are found in marine or estuarine waters. Most seagrass species are located in silty or sandy sediments. The seagrasses tend to develop extensive underwater meadows as they rapidly propagate by extension of the rhizome.
Seagrasses are believed to be derived from terrestrial plants that returned to the sea by progressive steps of acclimation to shallow fresh water, then to shallow brackish water, and finally to submersion in marine water. The adaptation to a submerged life in marine waters involves a complex set of morphological and physiological changes. In most species, flowering, fertilization, and seed production occurs underwater.
8. List 3 ecological roles seagrasses have.
Tank 15:
9. What type of symbiotic relationship does the anemone fish have with the anemone?
10. How does the anemone fish avoid getting stung by its anemone host?
Tank 18:
Giant Clams, Tridacna (also, more info as you exit to outside galleries and outside by by tank 64)
The giant clams belong to the phylum Mollusca, class Bivalvia. Note the fleshy, colorful mantle. Endosymbiotic zooxanthellae live inside the mantle tissue, providing nutrition for the clam via their photosynthetic products. Note the large incurrent and excurrent siphons, and look inside the siphon to see the large ctenidia (gills). Though tales abound of divers getting a foot or leg trapped between the two halves of a giant clam’s shell, the two halves cannot be drawn together closely enough to pose such a threat to humans. Imperiled throughout many parts of their natural range due to over-harvesting, giant clams are presented aquacultured at several facilities throughout the southwestern Pacific.
11. The giant clams filter food across their ctenidia. What is another source of nutrition for these giant clams?
12. List two major decomposers of the marine environment.
Tank 16:
Lagoon Coral Community
The calmer, protected waters of the lagoon environment harbor a different assemblage of corals than is found in the more exposed, turbulent waters of the surge zone. Both stony corals (with calcium carbonate skeletons) and soft corals (with flexible skeletons of gorgonin) are found here as well, but note the occurrence of different species than are adapted to the surge zone.
13. What features of these corals suggest they are adapted to calmer waters?
Display 19:
Barrier Reef
14. What role do herbivores have in maintaining the reefs’ diversity?
Cephalopod Gallery
As you leave the South Pacific Marine Communities Gallery, there are a series of tanks along the wall in front of you that display cephalopod molluscs. Like other molluscs, members of the Class Cephalopoda have soft, muscular bodies. But most cephalopods lack the familiar hard shell that many other molluscs have. They are named for their well-developed head and multiple arms: “cephalo-“ means head and “-pod” means foot. Unlike most other molluscs, many cephalopods are pelagic, adapted for life in the water column; some are benthic, living on the seafloor.
Tank 12:
Chambered Nautilus, Sole Survivor
Chambered nautilus are the most primitive of living cephalopods; they have an external shell, coiled in one plane and divided into chambers. The animal occupies the outer-most chamber; earlier chambers are closed off and used in maintaining neutral buoyancy.
15. What type of habitat is utilized by the chambered nautilus on a daily basis?
Tank 42:
Octopus: Brains & Brawn
16. The skin of many cephalopods, such as this octopus, contains pigment cells called chromatophores that enable the animal to undergo an array of changes in skin color or pattern. What might be the advantage of such color/pattern changes?
17. How does the octopus move through the water?
Ocean Drifters: Sea Jellies Exhibit
Jellyfish belong to the phylum Cnidaria, class Scyphozoa, in which the medusa form generally dominates in the life cycle. The tentacles develop on the oral surface, dangling down as in the mobile lagoon jellyfish (Mastigias papua) on display, or oriented upward when the animal is resting on the bottom. The tentacles are armed with batteries of cnidocytes, unique cells that function in defense and in the capture of prey. Each cnidocyte contains a stinging capsule, the nematocyst, which is discharged by touch or by certain chemicals.
18. How might radial symmetry, rather than bilateral symmetry, be advantageous to jellyfish?
19. What life cycle stage is the moon jelly in?
Gallery 2: Hawaiian Marine Communities
Tank 22:
Surge Zone, Koko Head
Within this tank are a number of corals that are adapted to the turbulent seawater motion found in shallow surge zones of coral reefs. Unlike their jellyfish relatives, in which the medusa form predominates in the life cycle, anthozoans occur only as polyps. The stony corals (order Scleractinia) live as solitary or colonial forms and secrete a hard external skeleton of calcium carbonate. Each polyp generation builds on the skeletal remains of earlier generations to construct living “rocks” with shapes characteristic of the species. The more flexible, whip-like soft corals (order Gorgonaceae) are also colonial forms comprised of polyps, but have a central axial rod composed of an organic substance called gorgonin that functions as a skeletal support. The tissues of both hard and soft corals harbor endosymbiotic algae called zooxanthellae, which pass much of their photosynthetic products to the coral tissue, thus providing a substantial contribution to the coral’s energy needs.
20. How is each type of coral skeleton (i.e., hard and soft) adapted to withstand the turbulent water of the surge zone?
Observe the few organisms that are able to survive on the wave-scoured rocks.
21. To what phyla do they belong?
22. What features of their morphology enable them to survive in this harsh environment?
Tank 23:
Sheltered Reefs, Kaneohe Bay
In the South Pacific marine communities gallery, you saw that a different assemblage of cnidarians flourished in the sheltered lagoon than in the wave-swept surge zone. Similarly, a more lavish assortment of organisms survive in the sheltered waters of Kaneohe Bay than on the exposed rocks around Koko Head. Note in particular the greenish, fleshy, colonial, sea anemone-like organisms here. Like corals and sea anemones, they belong to the phylum Cnidaria, class Anthozoa. They belong to a separate order (Zoanthidia), however, and are commonly referred to as zoanthids. Members of this order are largely tropical; some reef species pave rocks or form large encrusting masses and harbor zooxanthellae.
23. What features of the cnidarians found here distinguish them from those found in the surge zone environment?
Tank 24:
Young Reefs, Kona Coast
24. Members of at least 3 invertebrate phyla can be found in this tank. What phyla are they?
Tank 25:
Deep Reefs, Lanai
25. Why do you think the lavish assortment of corals found in shallow waters are lacking at depth, such as the 100-foot depth portrayed in this tank?
Gallery 3: Sharks, Jack, Trevaly, Grouper, Cleaner Wrasse
Display 28:
There are several Hawaiian Cleaner wrasse in this tank. Observe their behavior. They are small, so you need to look carefully.
26. Why do the predators in the tank not eat them?
Sharks are well designed for their role as a top predator.
27. What type of material is a shark’s skeleton made from?
28. List 4 methods to minimize the risk of encountering a shark
Gallery 3 (Display 37)
Sea Horse Gallery
29. What is the function of the leafy dragons’ elaborate appendages?
30. Where is the leafy dragon found?
31. Which parent broods the eggs and where are the eggs placed?
Wall Display, Problem Solvers, the Molluscs
32. Name 6 different types of roles in food webs that are played by different molluscs.
33. Choose one of these modes and describe the anatomical feature(s) that enables this type of feeding.
Tank 42:
Wrasses
34. Juvenile wrasses often look very different than the adult. Why is that?
Tank 43:
Ambush predators
35. How does the frogfish catch food?
Tank 46 and Wall Display
Hawaiian Fish Ponds & Ancient Hawaiian Artifacts
36. List 3 tools used by ancient Hawaiians to catch fish.
37. Describe how a fish pond works.
38. In the Ancient Hawaiian Artifact display is Triton’s Trumpet, which was used as a calling device. To what phylum does the Triton’s Trumpet snail belong?
39. What is an important way in which this organism contributes to the ecological balance of the reef?
40. What might be the effect of removing all the Triton’s Trumpets from a reef?
Gallery 4: Fisheries and Conservation
Tank 50:
Ornamental Aquaculture
41. What is the purpose of ornamental aquaculture?
Tank 52:
Responsible Fish Keeping
42. What should you not do with your home aquarium fish when you cannot care for them anymore?
Display 54 (not numbered):
The Reef Machine
Most of the animals in this tank are cnidarians. Look at the radial symmetry apparent in the large, fleshy polyps of some of the coral species. The centrally-located “mouth” (opening to the gastrovascular cavity) is surrounded by a circle of tentacles used for feeding and defense.
43. What might be the advantage of radial symmetry for these animals that are attached to the bottom?
There are also several types of holothurians, or sea cucumbers, on the sandy bottom of this tank.
These animals feed by ingesting sand & other sediment and digesting the organic matter adhering to the sediment particles. They have a 1-way digestive tract.
44. To what phylum do they belong?
45. What structures, unique to this phylum, facilitate the animal’s movement?
Before leaving the indoor displays via the Exit beyond Gallery 4, look at the shell from a giant clam. Notice the huge hinge, and the nacreous layer lining the inside of the shell.
46. What roles do giant clams play in the reef ecosystem?
EXIT to the outdoor displays.
Edge of the Reef (Display 55)
As suggested by several of the tanks inside (e.g., surge coral community, lagoon coral community), coral reefs are composed of a variety of habitats, each characterized by a suite of environmental features (e.g., depth, light penetration, water movement) and a diversity of organisms that are adapted to these features.
47. This outdoor display highlights 6 Hawaiian shoreline habitats. What are they?
48. Choose 2 of these habitats and describe the salient environmental conditions characterizing each. What kinds of invertebrates would you expect to see in each of these two habitats?
Tank 60:
Monk Seal
The monk seal is endemic to Hawaii and on the endangered species list, with a population estimated at 1,200.
49. What organism is a natural predator of monk seals?
50. Name three other causes that effect the monk seal population?
I hope you have enjoyed your visit to the Waikiki Aquarium. Feel free to return to displays that particularly interested you, or to examine some of the displays that were not included in these exercises.
If you did not come with the class, be sure to have this worksheet stamped by the attendant at the front gate as you leave!
Answer Sheet
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