Sea Urchins and Salmon

Sea Urchins and Salmon

Natalie Durland

General Information

A picture of me by the first exhibit.

A statue of an octopus near the entrance.

I went to the Seattle Aquarium on Thursday, February 15 from 3:30 to closing time. I picked the aquarium since snowshoeing was a significant time commitment and I'm familiar with the zoo but the exhibits at the aquarium are still new to me.





Life on the Edge

Sea urchins rooted themselves in the sand.

The Life on the Edge exhibit featured two long and shallow pools of water filled with sea anemones, sea urchins, sea stars, etc. (just like in Finding Dory). The organisms inside the pools were loosely organized by species and water depth: sea anemones grouped together in one of the deeper areas, sea stars clung to the same walled area, etc.

Some organisms, like sea urchins, rooted themselves deep in the sand to resist the waves. Other organisms resisted the waves by clinging to the wall of the seabed partially above the tide (sea stars) or burrowing underneath the sand (sand dollars). Most organisms also bent with the waves. Sea anemone tentacles floated freely in the water and sea feathers ruffled silently with every wave.

This octopus curled up to reduce surface area.

Different species used similar techniques to retain water and avoid desiccation. For example, several popular techniques like aggregation/ grouping involved reducing exposed surface area. Some species, like small fish and sea urchins, grew in large groups to reduce individual exposed surface area (aggregation). The octopus at the aquarium similarly reduced surface area by curling up (which also helped it hide from predators). The techniques varied with the vertical depth of the organism: species that were completely submerged in water (e.g. fish, sea urchins, anemones) tended to aggregate and species in upper tidal or shallow zones would burrow under the sand (sand dollar) or cling to a rock or wall (sea star). Organisms in the upper tidal zones also often had a shell (hermit crabs) to reduce exposed surface area and retain water.

The tentacles of this sea anemone bent with the waves.

It was interesting to note the size difference between prey and predator. One of the organisms in the exhibit was a fish-eating sea anemone that could consume a whole fish that appeared to match its mass/ volume. Similarly, hermit crabs and sand dollars eat most prey their size or smaller. Although it's not unusual for a human to eat something larger than a human (like a cow), it's odd to find a wild terrestrial animal that eats something nearly its own size.

Cliff habitats provide variety.

Birds and Shores

The next exhibit at the aquarium illustrates how some species of birds adapted to cliff faces and shorelines. It was surprisingly colorful with various natural shades of gray on the rock and a whole range of sandy to ebony colored rocks, sand, and shells on the shore. Active birds explored the water and sand in search of food and tired birds rested in niches and mini caves in the cliff face.

Natural crevices double as nests.

The natural holes in the cliff face provided nests for the birds. Without them, the birds would have to sleep, lay eggs, and raise eggs in the open, completely exposed to predators and the elements. If coastal erosion smoothed the cliff face over time, perhaps through strong winds, the birds would either die out or adapt to building nests in trees or on the ground. However, if industrialization destroyed or smoothed the cliff face in a week, the birds wouldn't stand a chance against natural shoreline predators.

Erosion grates on this rock's nerves.

Any immediate shoreline modification could also destroy the birds' food sources. Constant wave motion and daily tidal motion shift the contents of the sand and turn up new food and prey for the birds every day. Birds like the long-billed curlew and the black oystercatcher adapted to this food source and depend on it. Any kind of pollutant or construction on the beach would disrupt their diet and force the current community to adapt or move.

Salmon in our Watershed

These small fish swim together in a group.

The pollutants and structures like dams that come with industrialization threaten the livelihood and lifestyle of wild Pacific Northwest salmon. Chemicals released into the environment that mimic essential hormones like estrogen can decrease salmon mortality and reproductive rate and dams can obstruct the path of salmon towards freshwater spawning areas. Industrialization also increases the salmons' vulnerability to natural dangers like the tricky transition between salt water to and freshwater and natural predators (e.g. birds, bears, and otters).

The Seattle aquarium website describes salmon as a "keystone species", meaning that it "has a disproportionately large effect on its ecosystem" (Wikipedia). Although we should conserve salmon for tribal cultures and for its food value for humans, salmon conversation efforts are also essential because the pacific northwest ecosystem depends on salmon to transfer minerals from the ocean to land.


Reflection

Manta shrimp blend into colorful habitats.

My experience at the aquarium strengthened my understanding of true evolutionary diversity. In the ocean, organisms can adapt to exploit incredibly different food sources and implement completely distinct protective techniques and achieve similar ends (fueling cells and passing on genes).

The most fascinating to me was, by far, the amazing colors and designs of both ocean habitats and the organisms that occupy them. The manta shrimp especially demonstrates the incredible ability of an organism to blend into a conspicuous environment by being conspicuous.

This shell prevents desiccation.

Marine organisms evolved to survive and pass on their genes, but they also evolved into beautiful and/ or fascinating creatures that remind me of what it was like to be a toddler learning about clouds or dinosaurs for the first time.

The underwater dome is incredible.