Name: Yuzhu Gong Due Date: 2015/10/11
Article Title: The Prolific Afterlife of Whales
Author/Source: Scientific American
Article Title: The Prolific Afterlife of Whales
Author/Source: Scientific American
A: List major ideas, concepts or key points - point by point
- A single dead whale can nourish a specialized ecosystem that lasts for decades.
- Some signs suggest that whale-fall ecosystems have exchanges with other deep-seafloor communities, such as hydrothermal vents.
- Species similar to those at whale falls may have depended on dead marine reptiles for hundreds of millions of years.
- Mussels are found in recovered whale bones.
- Whale skeletons might act as stepping stone for these deep sea animals to spread from one chemosynthetic community to another.
- It has 3 partially overlapping ecological stages.
- The first, which they called the mobile scavenger stage, starts when the whale carcass arrives on the seafloor.
- The second stage, called the enrichment opportunist stage, lasts up to two years. During this period high-density, though low-diversity, communities of animals colonize the sediments surrounding the whale carcasses and the newly exposed bones.
- Sulfophilic stage, Specialized bacteria anaerobically break down lipids contained in the bones.
- A whale skeleton is extremely rich in lipids.
- Osedax is closely related to the giant tube worms that live at many vent and seep communities, it is also known as zombie worm.
- Chemosynthetic bacteria, they take O2 from the seawater to oxidize the sulfide, generating energy for growth.
B: Summarize the author's main point or idea
Whale carcasses can last for years or even longer than that, sometimes decades. Additionally, after they died, it will form an ecosystem in their skeletons by 3 steps. A dead whale that sinks to the seafloor brings a sudden bonanza of food to the dark, desertlike expanse. The community of organisms that springs up undergoes three ecological stages. Each stage is characterized by different species and different food webs— although at many such sites, the stages can overlap. The first stage is scavenger stage, primordial relatives of vertebrates that are virtually blind and live on the muddy seafloor—eat much of the blubber and muscle tissue, helped by other scavengers, including sleeper sharks and some crabs. It can last for two years. The second stage is opportunist stage. Animals feed on leftover scraps of meat and blubber and on whale oil that has soaked the surrounding sediment. This second wave of scavengers includes snails, bristle worms and hooded shrimp. Meanwhile “zombie worms” [see illustration on page 84] begin to spread their roots into the bones and feed on their lipid content. The final stage is sulfophilic stage. Anaerobic bacteria produce hydrogen sulfide, which other, “sulfophilic,” bacteria use for energy. The sulfophilic bacteria, in turn, support all other organisms (inset at bottom). Mussels, tube worms and clams derive energy from sulfophilic bacteria that live symbiotically within them. Bristle worms and limpets feed on mats of such microbes. Crustaceans such as squat lobsters prey on other animals. It can last for 50 years. There are two reasons that discrepancy exists in this case study, first is the experimental sites, second is might be the activities of the extraordinary worm Osedax.
Whale carcasses can last for years or even longer than that, sometimes decades. Additionally, after they died, it will form an ecosystem in their skeletons by 3 steps. A dead whale that sinks to the seafloor brings a sudden bonanza of food to the dark, desertlike expanse. The community of organisms that springs up undergoes three ecological stages. Each stage is characterized by different species and different food webs— although at many such sites, the stages can overlap. The first stage is scavenger stage, primordial relatives of vertebrates that are virtually blind and live on the muddy seafloor—eat much of the blubber and muscle tissue, helped by other scavengers, including sleeper sharks and some crabs. It can last for two years. The second stage is opportunist stage. Animals feed on leftover scraps of meat and blubber and on whale oil that has soaked the surrounding sediment. This second wave of scavengers includes snails, bristle worms and hooded shrimp. Meanwhile “zombie worms” [see illustration on page 84] begin to spread their roots into the bones and feed on their lipid content. The final stage is sulfophilic stage. Anaerobic bacteria produce hydrogen sulfide, which other, “sulfophilic,” bacteria use for energy. The sulfophilic bacteria, in turn, support all other organisms (inset at bottom). Mussels, tube worms and clams derive energy from sulfophilic bacteria that live symbiotically within them. Bristle worms and limpets feed on mats of such microbes. Crustaceans such as squat lobsters prey on other animals. It can last for 50 years. There are two reasons that discrepancy exists in this case study, first is the experimental sites, second is might be the activities of the extraordinary worm Osedax.
C: Reaction to the article
A single dead whale can nourish a specialized ecosystem that lasts for decades. Some signs suggest that whale-fall ecosystems have exchanges with other deep-seafloor communities, such as hydrothermal vents. Species similar to those at whale falls may have depended on dead marine reptiles for hundreds of millions of years. The clams and mussels belonged to groups known to harbor chemosynthetic bacteria. Such bacteria can draw energy from inorganic chemicals, and they sometimes form the basis of entire ecosystems. (The earliest organisms, before life “invented” photosynthesis and introduced oxygen into the biosphere, were chemosynthetic, although they had a different metabolism from that of modern chemosynthetic organisms.) Most of the mollusks were known only from other chemosynthesis-based sites: the mussels from sunken wood and hydrothermal vents; vesicomyid clams from vents and cold seeps, where fluids rich in methane and other hydrocarbons leak onto the seafloor; lucinid clams from seeps and anoxic sediments (seafloor sediments lacking oxygen); and a snail from anoxic sediments.
A single dead whale can nourish a specialized ecosystem that lasts for decades. Some signs suggest that whale-fall ecosystems have exchanges with other deep-seafloor communities, such as hydrothermal vents. Species similar to those at whale falls may have depended on dead marine reptiles for hundreds of millions of years. The clams and mussels belonged to groups known to harbor chemosynthetic bacteria. Such bacteria can draw energy from inorganic chemicals, and they sometimes form the basis of entire ecosystems. (The earliest organisms, before life “invented” photosynthesis and introduced oxygen into the biosphere, were chemosynthetic, although they had a different metabolism from that of modern chemosynthetic organisms.) Most of the mollusks were known only from other chemosynthesis-based sites: the mussels from sunken wood and hydrothermal vents; vesicomyid clams from vents and cold seeps, where fluids rich in methane and other hydrocarbons leak onto the seafloor; lucinid clams from seeps and anoxic sediments (seafloor sediments lacking oxygen); and a snail from anoxic sediments.