What are the three Whale Fall stages, and what are the main organisms in each of them?
- Stage 1: Mobile-scavenger stage (sharks, invertebrates, rat-tails, hagfish)
- Stage 2: Enrichment opportunist stage (crustaceans, mollusks, polychaete worms)
- Stage 3: Sulphophilic (sulphur-loving) stage (Sulphur-producing lipid degrading bacteria, Chemoautotrophic bacteria, Mussels, tube worms, calms bristle worms, limpets, fish)
Explain “sexual dimorphism” in Osedax.
- in most species of osedax, there are large females and microscopic males
- main purpose of the male is to release sperm to fertilize the eggs
- one exception, similar sized genders with internal fertilization
Discuss Osedax eggs buoyancy in relation to their ecological niche.
- eggs are neutrally or negatively buoyant
- need to settle on a substrate, so more logical to not float
What are the different body parts of Osedax?
- top is palps/crown: gills of the organism
- attached to trunk
- attached to roots, which burrow into the bone
Describe the three-step process for Osedax nutrition. How do they dissolve the bone? How do they take up collagen, amino acids, and lipids? How do they digest these compounds?
- excrete acid to dissolve bone calcium phosphate, and proteases to release collagen and lipids
- absorb nutrients and transport to bacteria
- transport collagen and lipids in vesicle (transcytosis), amino acids are transported using amino acid transporters
- has trophosome which contains symbiotic heterotrophic bacteria
- bacteria produce more diverse metabolites, which are transferred back to worm
- osedax also digests bacteria
Why do Osedax roots require an abundant oxygen supply to be able to excrete acid and dissolve bones?
-O2 used for production of CO2 and excretion of acid
Acid secretion for bone dissolution is associated with the absorption of bicarbonate. What type of acid-base disturbance is it?
-metabolic alkalosis (caused by addition of HCO3-(e.g. post-feeding))
What other cell types and organisms use an acid-excreting mechanism that is similar to that in Osedax root cells?
-giant clams secrete acid to bore into coral reefs
Describe how (and where) the giant clam uses some cellular mechanisms that are similar to coral, and other that are similar to Osedax.
- VHA in the siphonal mantle of giant clams and the coral symbiosome promotes algal photosynthesis by keeping low pH for contained symbionts
- VHA in pedal mantle of giant clams and osedax root both secrete acid
