GES1021 Lecture 5 Intertidal and Subtidal habitats PDF

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Intertidal and subtidal habitats ...

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GES1021 Lecture 5 Subtidal habitats Poster assignment: Due on 3 April 2019 A3 poster, about 3 introduced animals and 3 introduced plants of a certain habitat and their impacts on the environment. Meant to be an educational poster catering from children to govt officials

Tubeworms: part of the tube is exposed, tubeworms attach stones to their exposed part for extra structural strength. They filter feed Christmas tree worms: Very attractive, come from the Caribbean. Believed they were brought in due to the shipping industries and private yachts from the carribean. Part of a mutual introduction of organisms between Singapore and the rest of the world. One organism of two parts Sea cockroach (ligia spp)- not really related to cockroach but are useful as bioindicators. If you go to a habitat that is very disturbed there will be many sea cockroaches. Study done has discovered there are many (cryptic?) species of sea cockroaches, not just one or two Hermit crabs- when they moult they have to shed the whole shell and find a bigger shell to squeeze into. Will have a whole row of hermit crabs lined up from biggest to smallest to exchange shells with each other. Easy to keep as pets. Hermit crabs MUST live inside their shells. Giant isopods- found in java sea around Singapore Marine snails- secrets protective calcium carbonate shell throughout life. Operculumfunctions as a front door (protective seal) for the shell. Hard shell protects from predators and dessication. Top shells- usually eaten for festive occasions in Singapore Black-lipped conch (gong gong)- eaten by people in Singapore Red chut-chut snail- eaten by people in Singapore, fried in chilli Cowries- type of mollusk shell, used for jewelry. Cowrie can extend its foot across the entire shell to clean any dirt from it, shells used as currency in certain Polynesian countries Xanthid crabs- small crabs at maturity, colourful. Pilummid crab found in encrusting communities on buoys off the coast of SG. Scientific name named after the lee family that funded the LKC museum as a show of gratitude Velcro crab- tiny hairs on its body, will stick anything it can find onto its body to camouflage itself

Fiddler crab- males have one big claw and one little claw- big claw used to protect its territory and show its dominance and attract females. Every species has a different shape and colour of claw and its own distinct wave to tell each other apart. Male burrows and female burrows come close, but never into contact with each other. Brittle stars: arms are very tender, easy to break off. Brtittle stars can move very fast, exist on Singapore shores too Knobby sea stars: very big and heavy sea stars due to nodules found on their topside Sea cucumbers: some are not meant to be eaten! Especially colourful sea cucumberscolourful and bright colour means dangerous. Sea cucumbers expel their intestines as a defense mechanism, is ok for them as they can regrow these parts Sea urchin: relative of sea cucumber, have brittle spines that can break off in your feet if you step on them. Need to break the spine into tiny pieces so the body can dissolve them Horseshoe crab: uses its tail to right itself. Important organism in our ecosystem- appeared before dinosaur came out, and haven’t changed its form until now. In the last 10+ years the horsehoe crab’s blood is valued by people for its medicinal properties. Horsehoe crabs are caught by pharma companies and bled dry to Frogfishes (type of angler fish): uses its antenna as a lure to catch prey

SUBTIDAL HABITATS Organisms only visible before a tsunami Land reclamation buries subtidal habitats and sedimentation from land reclamation affects areas uninhabited Smith-mcintyre grab- lower from the boat to seafloor, once lowered, it will scoop up sediment for further examination Dredges- scrapes the bottom of the seafloor and scoops up sediments for examination. Very damaging to shallow seafloor For deep sea research- need submersible to explore the deep sea. Only room for crew of 1 or 2. Soft bottom habitat types: sandy/muddy/different mix of both Sunken ships provide additional habitats for organisms Soft-bottom benthic habitats are very diverse habitats Number of families of Singapore’s benthic organisms vary according to development of these areas- eg. after the cleanup of the Singapore river in 1995, the number of benthic families recorded increased. Number of benthic communities can be used as indicators of environmental changes Common benthic organisms - Sea fans: related to corals, harvested and made into jewelries - Sea pens: look like ancient feather pens, also used for jewelry, associated with crabs: sea pens will live with crabs, who will pass on food leftovers to crabs

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Noble volute: egg cases found outside shell Sponges: contain bioactive compounds that can be used for medical treatment Baler shell: giant shell, very spectacular. Live shells only found underwater, and may come up to intertidal area sometimes Basket star: used to be thought to be extinct, but only recently discovered by fishermen. Arms keep branching out to form a “basket” structure Solefish and chut chut and lala clams- benthic animals used for food

Subtidal habitats: open sea - Three lifestyles: drifting (carried by the water), swimming( can move independently) and benthos (bottom dwelling, stationary) - Sunlight can only penetrate 7m of water column,made worse by sediment in the water, below this depth, no plants will be found. Means water gets colder and pressure is higher the further down the water column you go. Even sound changes with the increasing depth. - Plants found in the subtidal area: - Sargassum: used as meeting and rest place for fish - Red tides (dinoflagellates): biolumsicent, create a blue light due to stress when they are subject to the force of the waves. Cannot eat seafood that has consumed the red tide, as they contain saxitoxin which will cause paralytic shell poisoning...