Unformatted text preview: Marine benthic Marine benthic invertebrates
Spineless creatures! Marine Nitrogen cycling
N2 phytoplankton NH4 N2 fixing
“New N” excretion zooplankton “New N”
Advection/diffusion fecal pellets
denitrifyers NH4 NO2
to deeper water Nitrifying
aerobic Bacterial remineralization
NH4 PON to sediments Below photic Zone N2O larger zooplankton/ Fish Photic zone DON release NO3 Air N2 Invertebrates
Invertebrates About 97% of all species of animals on earth are invertebrates, and many of these are marine.
Interestingly, only one insect, Halobates, a water strider, spends its whole life in the ocean. Sponges (phylum Porifera)
Sponges (phylum Porifera) The simplest of the invertebrates is the sponge.
Don’t form tissues or organs.
Sponges are filter feeders and pump water in through ostia and out through the osculum.
A phylum is a taxonomic group of organisms all of which are related in their characteristics. It is a major grouping which falls just under Kingdom. Plants are one Kingdom & Animals are another Specialized cells (choanocytes) move water through the Specialized cells (choanocytes) move water through the sponge by beating cilia. The collar on the choanocyte is used to trap food for the sponge colony The body of a sponge usually gets support from spicules The body of a sponge usually gets support from spicules which are either siliceous (silicon) or calcareous (calcium). They are of various sizes and shapes Support in the sponge comes also from a protein called spongin. Support in the sponge comes Bath sponges are the spongin skeleton with the living material removed (most kitchen sponges are made of cellulose and aren’t derived from sponges) Spongin
Spongin Electron microscope photo of spongin in a bath sponge. The spongin is elastic and can hold lots of water in the spaces in between. Sponge reproduction
Sponge reproduction Can reproduce by budding in which the bud falls off and becomes a new sponge.
Can also produce gametes (eggs & sperm) which are released into the water either within the sponge or outside and they join to form an embryo.
A tiny sphere of cells with flagella (a larva) is then formed and drifts with the current.
The larva later settles and forms a new sponge colony. Many sponges have symbiotic algae (Zooxanthellae) Many sponges have symbiotic algae ( living in their tissues. The algae photosynthesize and provide some food for the sponges Sponges are not found just in the tropics but are Sponges are not found just in the tropics but are distributed from tropics to the poles. Several sponges produce chemicals that show promise in fighting cancer and human diseases Why would sponges have anticancer Why would sponges have anticancer chemicals? Sponges are sessile (can’t move). So if something tries to grow on them, they need protection to keep it off.
The protection is chemicals that prevent the invader from growing. These chemicals can also act on cancer cells and prevent them from growing.
Many sponges now being tested. Anti Cancer Sponges
Anti Cancer Sponges Two examples Phylum Cnidaria
Phylum Cnidaria Jellyfish, sea anemonies, corals & hydroids
They are radially symmetrical
A step up from sponges since they have different tissues
A tissue is a group of cells specialized for one function
Inner & outer body walls are separated by a gelatinous layer called the mesoglea which doesn’t contain cells.
A central mouth leads to baglike digestive tract, the gastrovascular cavity. They have no anus.
Mouth surrounded by tentacles.
There are plenty of planktonic cnidaria (common jellyfish), but we will focus on the benthic forms Radial Symmetry
Radial Symmetry Mesoglea is a gelatinous layer in Mesoglea is a gelatinous layer in middle that doesn’t contain cells Cnidaria have no anus. Wastes enter & Cnidaria have no anus. Wastes enter & leave the gastrovascular cavity through the mouth Cnidarians can exist as a free swimming medusae (L) or an attached polyp (R). Cnidarians can exist as a free swimming Mouth faces down in medusae and up in polyp. Many species have life cycles that alternate between the two stages. Medusae can produce eggs & sperm which will turn into polyps and polyps can produce medusae by budding. Nematocysts are stinging cells which Nematocysts are stinging cells which can be used for defense or for obtaining food Nematocyst stings can leave Nematocyst stings can leave permanent scars It is a myth that peeing on jellyfish It is a myth that peeing on jellyfish stings will cure it Use Vinegar, as it is acidic and will discharge stinging cells The clown fish has a layer of mucous which prevents The anemone nematocysts from harming it. It receives protection from predators by living among the anemone tentacles. In this symbiosis, the clown fish chase away fish such as butterfly fish that want to eat the anemone Anthozoans are cnidarians which are polyps that lack a Anthozoans medusa stage. They consist of anemones, sea fans, corals, and sea pens etc. Cnidarians
Cnidarians Most cnidarians are carnivores
Use their nematocysts to capture prey
Lack a brain but have a nerve net which connects the cells and transmits impulses
Some are able to sense light and are able to detect whether nearby jellies are closely related or not. Corals
Corals Corals are also cnidarians. We will cover them in more detail in the benthic lecture Ctenophores (Sea Gooseberries) are another Ctenophores (Sea Gooseberries) are another phylum and are not Cnidarians
even though they look like them They have no nematocysts They have rows of cilia to make them move Flatworms are another more advanced phylum. They are Flatworms bilaterally symmetrical, simple organisms with tissues are organized into real organ systems. They may be free living carnivores or parasites (tapeworms or flukes). Have a mouth but no anus. Live in/on sediments. Ribbon worms (Nemerteans) are more complex than flatworms and have Ribbon worms
a circulatory system, mouth & anus. Have a proboscis (long fleshy tube to c ensnare prey). The proboscis has a toxin. They are carnivores and common in shallow temperate waters Nematodes (roundworms) are another phylum very common in Nematodes
sediments. Have mouth & anus and mostly feed on bacteria. Some are parasitic and live in flesh of fish (beware of Sashimi & Ceviche ). Can infect humans. Phylum Annelida: Segmented worms. In the sea consist Phylum Annelida: Segmented worms
mostly of polychaetes in which each body segment has stiff bristles Polychaete worms
Polychaete worms Have a circulatory system. Have gills near the setae (bristles on sides of body) to obtain oxygen.
Have a trochophore larvae (Rt) to disperse the species as a planktonic stage Many polychaetes build tubes of mucus, Many polychaetes build tubes of mucus, protein or other material. They usually live in the sediment and are suspension feeders. Two types of feeding in benthos
Two types of feeding in benthos Suspension feeders filter plankton & detritus out of water that passes by to obtain food
Deposit feeders get their food by eating the sediments and digesting bacteria and other food particles There are many other phyla of marine invertebrates living in There are many other phyla of marine invertebrates living in sediments such as peanut worms (left) or echiurans (right),
but not enough time to cover them here. Molluscs
Molluscs Consist of a very diverse phylum
Snails, clams, squid, octopuses
Body not segmented
All have a radula, a ribbon of small teeth used to feed.
All have a mantle, thin layer of tissue that secretes a shell.
Have more species in ocean than any animal group (>200,000) Many molluscs are highly advanced
Many molluscs are highly advanced Most have separate sexes but some are hermaphrodites (have both male & female sex organs in one individual)
Squids & octopus have highly advanced nervous systems
All molluscs have a circulatory system that transports nutrients and oxygen. Radula: used to rasp on surfaces for Radula: used to rasp on surfaces for feeding Mantle secretes shell
Mantle secretes shell Bivalve anatomy
Bivalve anatomy Molluscs
Molluscs Consist of several different subdivisions
Gastropods: snails, limpets, abalones, (one shell) nudibranchs
Bivalves: clams, mussels, oysters (2 shells)
Cephalopods: Octopuses (not called Octopi), squid, cuddlefish (no shells)
Others: Chitons & tusk shells Molluscs: Gastropods (stomach footed) Molluscs: Gastropods (stomach footed) consist of snails, limpets, abalones & nudibranchs Most feed by using radula to scrape algae from hard surfaces but some are carnivores
Others drill into oysters, are deposit feeders in mud or are carnivores like cone shells. Molluscs: Nudibranchs are gastropods which have lost their Molluscs: shell in evolution. Very colorful. Prey on sponges and other invertebrates. Many have poisons for defense. They pick up the toxins by eating poisonous sponges and the stinging cells of cnidarians, and they store the poisons in their tissues Molluscs: Cone shells are beautiful but very poisonous (neurotoxin). They Molluscs: Cone shells are beautiful but very poisonous (neurotoxin). They live in coral reefs and prey on clams, oysters, worms & small fish. Their toxins now used in neurobiology research. Humans can be severely poisoned by them. Cone shells attack fish with their Cone shells attack fish with their toxin Conotoxins are complex and can kill humans. “Hypodermic needle” at tip of proboscis Conus magus (Magician’s Cone) Proboscis Conus magus (Magician’s Cone) Proboscis has a poison which has over 200 peptides Prialt is a drug from the Cone Snail. Injected directly into human spine for chronic pain Coopers Nutmeg Snail lives along Coopers Nutmeg Snail lives along Cal coast. When Angel Sharks rest on the bottom the snail threads its proboscis into a vein in the gills and sucks the shark’s blood Muricid Snails are known as Oyster Muricid Snails are known as Oyster Drills They can drill though a bivalve shells using their radula. It then inserts its proboscis and eats the oyster. Can decimate oyster beds. Molluscs: Bivalves have a twovalved Molluscs: Bivalves have a twovalved shell Have circulatory system, gills for respiration. Shown
is a Pacific Geoduck Molluscs: Mussels secrete strong byssal Molluscs: Mussels secrete strong byssal threads for attachment (taste good too) Byssal Threads and their natural Byssal Threads and their natural glue are extremely strong Byssal Threads
The threads have a glue which works underwater. Extremely strong! Commercial application is to
Use this glue to replace urea
Formaldehyde in plywood
Since it works in liquids it is
Possible to use in surgery! Jason and the Argonauts
Jason and the Argonauts The Golden Fleece was made from byssus threads of a Mediterranean Pen Shell Pinna ragosa Royal Purple
Royal Purple The dye is prepared from Murex, and other species of seasnail, picked off the rocks. When the dyers squeeze or blow on the mollusks, they give off a foamy secretion which is rubbed onto a skein of cotton. Although it is initially colorless, contact with the air turns it yellow, green, and ultimately purple. Used by Roman and Greek royalty. Molluscs: Tridacna is largest bivalve Molluscs: Tridacna is largest bivalve and has symbiotic algae living in its tissues There are no records of divers being There are no records of divers being caught and drowning by Tridacnas. Another myth! Tridacna spawning Molluscs: Shipworms are bivalves (not worms) which bore Molluscs: Shipworms are bivalves (not worms) which bore into wood
Invaded SF Bay in 1913 and destroyed piers by boring through and eating the wood Cephalopods (also molluscs!)
Cephalopods (also molluscs!) Consist of octopus & Squid
Large, advanced eyes
Swim by forcing water through a siphon
Efficient hunters of crabs, lobster, squid, etc. Can have a toxic bite Cephalopod
Cephalopod Tattoo Cephalopod eye
Cephalopod eye Human & Cephalopod eyes very similar. We focus by changing the shape of our lens and they focus by moving the lens in and out Molluscs: Squids have a chitinous Molluscs: Squids have a chitinous “shell” which is called a “pen” It’s easy to remember squid It’s easy to remember squid anatomy! Molluscs: Chambered nautilus floats and has Molluscs: gas filled chambers in shell. It uses tentacles to capture prey. Last survivor of the predatory nautiloids from 450 mil yrs ago Chambered Nautilus Tattoo
Chambered Nautilus Tattoo Beautiful Mathematical Symmetry Arthropods
Arthropods Over a million known species worldwide (land & water…..Molluscs still have them beat in the Ocean)
Barnacles, shrimps, lobster, crabs, copepods etc.
Have segmented body, jointed appendages
Exoskeleton of chitin
To grow, must molt to shed old exoskeleton
Crustaceans are largest group of marine arthropods The Horseshoe Crab (Limulus) is The Horseshoe Crab (Limulus) is more closely related to spiders than crabs. It lives on the US east coast, and is a living fossil, remaining basically unchanged for 450 million years Limulus mate in spring in shallow Limulus mate in spring in shallow waters. Larvae are important as a food for migrating birds Limulus amebocyte lysate (LAL) is an aqueous extract of blood cells (amoebocytes) from the horseshoe crab, Limulus polyphemus. LAL reacts with bacterial endotoxin or lipopolysaccharide (LPS), which is a membrane component of Gram negative bacteria. This reaction is the basis of the LAL test, which is used for the detection and quantification of bacterial endotoxins. Arthropods: Barnacles
Arthropods: Barnacles Filter feeders
Look like molluscs but are crustaceans
Hermaphrodites and can act as male or female with another barnacle
Have larval stages so they can disperse Anatomy: Cirri are used to filter Anatomy: Cirri are used to filter food particles Note both ovaries & Testes & long penis Relative to body size the penis is Relative to body size the penis is longest in world 810X body length! Because adult barnacles are sessile, Because adult barnacles are sessile, they need a planktonic stage to disperse After fertilization, the eggs are brooded within the adult where they develop into naupliar larvae. Nauplia are released and drift for 1045 days and go through 6 naupliar stages in which they feed on phytoplankton and deposit lipid reserves Final planktonic stage is ciprid and it lives on fat reserves and doesn’t feed. Cyprid looks for a spot where there are other barnacles and attaches to hard surface The barnacle Chthamalus anisopoma in The barnacle Chthamalus anisopoma in Gulf of California is often attacked by the snail Acanthina Snail drills straight into barnacle “mouth” but if the barnacle is exposed young it will grow with its “mouth” sideways (upper drawing) so it is difficult for snail to penetrate. Problem Is that it has to Sacrifice part of gonads Arthropods: Amphipods & Isopods
Arthropods: Amphipods & Isopods Live in benthos
Scavenge among debris on bottom
Some parasitic on whales
Gray Whales feed on Amphipods in Alaskan waters Arthropods: Decapods (ten legs) are Arthropods: Decapods (ten legs) are shrimp, lobsters & crabs Mostly scavengers
Have many larval stages in plankton
Body consists of cephalothorax & segmented abdomen
Have compound eyes and are very sensitive to detecting chemical signals Other Marine Arthropods
Other Marine Arthropods Horseshoe crabs
Somewhat related to each other
Distant relatives of spiders & scorpions Echinoderms: starfish, brittle stars, Echinoderms
sea urchins, sea cucumbers & crinoids Radially symmetrical
Unique water vascular system Echinoderms: Starfish external Echinoderms: Starfish external anatomy Starfish move by reaching out with tube feet and pulling Starfish move by reaching out with tube feet and pulling themselves along. Tube feet controlled by a hydraulic system. Can prey on bivalves and latch onto shells with tube feet and slowly pull them apart. Next it extends its stomach into bivalve to consume it. Echinoderms: Brittle star
Echinoderms: Brittle star
Like a sea star but Have more flexible arms Echinoderms: Sea Cucumbers
Echinoderms: Sea Cucumbers Deposit feeders
Lay on bottom on its side
Tentacles help with feeding at mouth end
Has an anus
Some have toxins Sea cucumber skin is normally soft Sea cucumber skin is normally soft and flexible However if it feels threatened, it can make its skin rigid.
Scientists have figured out how this is done and are designing materials that can switch from soft to rigid A committed Marine Biologist
A committed Marine Biologist Rachel’s Sea Cucumber Echinoderms: Sea urchin & sand Echinoderms: Sea urchin & sand dollar
Endoskeleton is rigid Shell. Spines moveable. Sea Urchins feed on macroalgae Sand dollars are deposit feeders Review: Sea otters eat sea urchins and keep their populations down.
Review: Sea otters eat sea urchins and keep their populations down.
If predation by otters is low, the urchins overeat kelp and the kelp forests are reduced. Tunicates: Sea squirts Tunicates: Sea squirts Sea squirts are chordates
Have a larval stage which looks like a tadpole thus are related to primitive vertebrates
Adults simply filter water (salps & larvaceans are planktonic species) They are called sea squirts because when you squeeze them, they squirt Quick Review
Quick Review Today we covered these benthic invertebrates:
Polychaetes (segmented worms)
Cnidarians (jellies as polyps or medusa)
Molluscs (clams, squids, octopus, conchs)
Arthropods (lobsters, barnacles, crabs etc)
Echinoderms (Starfish, sea urchins, sand dollars, sea cucumbers, etc)
Tunicates (sea squirts) What to know
What to know Know difference between deposit and filter (suspension) feeders
Bilateral & radial symmetry
Evolution of digestive system from primitive sponges to more advanced organisms
Polyp, medusa, radula, nematocysts, exoskeleton
What organisms are molluscs (clams, squid, octopus, etc)
How echinoderms move
What are Arthropods…..crustaceans? Give example More
More How sponges are supported
How Clownfish is protected
What are corals
What marine animal group has most species
What is a Hermaphrodite
Some characteristics of Arthropods The End!
The End! ...
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- Fall '08
- Bacteria, Cnidarians, photic zone, molluscs