Shark Reproduction...

Today students learned an introduction to sharks. We talked about the history of sharks, common characteristics of cartilaginous fish and then the reproductive strategies of sharks.

Not a lot is known about shark reproduction because in many cases it has never been observed. Sharks have internal fertilization and the male shark has two claspers for sperm delivery. These can be seen on male sharks protruding from the pelvic fin.

Shark reproduction is violent with males biting the female. As a result female shark skin is much thicker than the males so that this practice does not ham or kill her. She fights a little to ensure that only strong males with good genes are able to fertilize her eggs.

Some sharks are oviparous and lay eggs (pictured). These egg cases are known as mermaid's purses. You can see the baby shark and its nutrient-rich yolk through the leathery egg case.

Some sharks are viviparous and have live birth a lot like mammals.

And some sharks are ovoviviparous and keep their eggs inside the uterus before releasing them... so its making eggs and then kind of having live birth.

Shark Senses

Today we learned about shark senses. Sharks have a large brain to help process the sensory overload they must get from the SEVEN senses they have. They have the five we have plus a lateral line (pressure and vibrations) and the ampullae of lorenzini (electro-reception).

Follow this link for a cool interactive about how shark jaws stick out when they attack their prey! The interactive is down at the bottom.

If you are doing a final project on a shark... check out this new link! www.shark.ch

And once again... one try only... how much do you know about sharks? MsJ scored a 1467. Try Shark Weeks Ultimate Shark Challenge to see how much you know. Please limit yourself to 15 minutes.

Why sharks are Amazing Predators

Shark Attacks - Who Should Be Afraid?

These are some of my favorite shark graphics.

Appreciate and LEARN. 

Click on the images to make them larger.

Starting sharks!

Next up is SHARKS! Great whites in the waters off the coast of South Africa leap out of the water to chase the fur seals they want to eat that also leap out of the water.

Try Shark Weeks Ultimate Shark Challenge to see how much you know. (Play only once) MsJ scored 1370.

Fishing - Harvesting FIsh

Netting is the most popular method of commercial fishing because a lot of fish can be caught in short amount of time without a lot of effort.

One the major problems with most commercial fisheries is the amount of bycatch. Bycatch is anything caught in the net that you do not want. This could include edible fish that your company is just not equipped to process.

Most organisms brought up in nets as bycatch do not survive because they are crushed or drowned. Sea turtles and dolphins sometimes get swept into nets and drown because they cannot make it to the surface to breathe.

Most scientists and fisherman agree that the oceans have been and are being overharvested. People may not like regulations, but without regulations, many fish species that we used to commonly consume would be extinct.

Intelligent Seafood Choices

We started discussing marine harvesting and fishing today by talking about who harvests the most seafood (China), who eats the most seafood (China), and which people eat the most seafood pounds per person (the Maldives). Americans are about sixth on the list as far as consumption, but we are the number one consumer and importer of shrimp. Importing shrimp is damaging to the environment for two reasons.

1. Shrimp that are farmed in other countries are not as regulated as here in the states, so shrimp farm pollution is not as regulated and it damages coral reefs. Also many mangroves are cleared to build these farms.

2. US boats are required to have turtle excluder devices (TED) on trawl nets so that turtles do not get caught in shrimp nets and drown. Other countries do not regulate this and as a result catch and drown sea turtles.

To make a environmentally responsible seafood choices, choose shrimp that are farmed or caught in the US. For more sustainable seafood choices, check out Seafood Watch.

I went prawn fishing while in NZ!

Fish Spawning

Fish reproduce in a variety of ways. Most are broadcast spawners, meaning that when the time is right, the females release their eggs, the males release their sperm and they both meet and mix producing fertilized eggs that develop into fish fry (meroplankton) and eventually into adult fish. These snapper are spawning and you can tell by the large cloud of gametes in the water.

By producing a lot of eggs, the snapper hope to overwhelm any predators trying to make a meal so that there is no way all the fry are eaten and some will have a chance of surviving. Course there are predators that time their arrival with this spawning to eat all those nutritious eggs and gametes.... Yum!

Fish Shapes - Body & Mouth

Today in class we discussed fish mouth shape and body shape and what they mean about the fish.

Many fishes are identified by looking at or into the mouth. The number of mouth-types exhibited by different species is nothing short of astonishing. Three lakes in Africa contained about 900 species of cichlids, nearly all differentiated mainly by the way their mouths are shaped. (This number is rapidly dwindling, by the way, as the cichlids in these lakes are driven to extinction). Cichlid mouths are variously adapted to eat other cichlids' eggs, scales pulled from fishes' living bodies, algae from rocks, tiny invertebrates, and many other forms of food. The arrowana of South America has a mouth adapted for spitting water with precision at insects perched on overhead branches. Parrotfish mouths have evolved to look and act like beaks, which they use to grind at coral, making the sand that surrounds coral reefs. Seahorses and pipefish have tubular mouths for sucking in small prey in narrow places like a vacuum cleaner.  SOURCE

Fish with forward facing mouths eat what is in front of them - no surprise. Downward mouths eat algae, prey below them like crustaceans and molluscs, or they take in mouth fulls of gravel, eat the particles, and spit the gravel back out. Upward facing mouths indicate the fish eats prey above them - typical of benthic ambush predators. There are also bills and beaks. Bills are long and skinny used for poking in crevices and eating plankton one at a time. Beaks are used for chomping and can be seen on the parrotfish, a fish that chomps on the algae growing on the surface of dead coral. Fish can also have very large mouths common on filter feeders and fish that swallow large prey whole. Fish also have teeth - a surprise to many - and come in many shapes and size.

Body shape also tells you a bit about a fish. Com- pressed fish have flash and look skinny and can only be found in slow moving waters like coral reefs. Fusi-form fish are tapered like footballs and are very streamlined for constant fast swimming. Depressed fish are benthic and squashed looking. Eel shaped fish are poor swimmers and live on the benthos or in cracks and crevices.

Here is a website you can use to identify shapes - realize they are named a bit differently than how I do in class.

Fish tails (caudal fin) indicate how fast and how much a fish swims. For this class, we are focusing on the crescent (not pictured), forked (e), square (d), rounded (b), and funky (c, f, h). As you can see there are more fish tail shapes out there.

Crescent caudal fins indicate a very fast fish that is constantly swimming - not time for resting, it is time to go go go! Forked caudal fins are the second fastest, and very maneuverable. Square fins are for your every day swimming fish - they have ok acceleration ad maneuvering. Round fins and Funky fins are slooooooow swimmers that don't spend a lot of time swimming. They can be quick for very short bursts. 

Jawless Fish

Today we discusses jawless fish. Jawless fish are primitive fish with a notochord instead of a backbone and a flat rasping mouth that cannot close like ours. As a result thes fish cannot bite... only scrape and hold on.

Pictured to the right, you can see five lamprey mouths and one lamprey head with blue eyes and seven gill holes.

Jawless fish include lampreys which are parasites and hagfish which are detritavores. Neither one will ever win a beauty contest.

Hagfish make slime to escape their predators... and it is quite gross. So gross that even they don't like it... so they tie their body into a knot to squeegee the slime off of themselves after evading a predator.

Invertebrates - Overview

Invertebrates do not have backbones and make up 95% of the animals living on earth (us vertebrates are actually way way way in the minority).

We have covered molluscs, crustaceans, and echinoderms in larger units, but there are lots of other invertebrate phyla including three types of worms, sponges, and cnidarians.

Cnidarians include coral, jellies, and sea anemones and will be covered in Unit 10. They have radial symmetry and stinging tentacles surrounding their mouth.

Sponges in phyla Porifera have asymmetry because of their irregular shapes. Water flows in through many small pores and out large centralized openings called osculum. This is how sponges get their food and how they get rid of waste. Sponges have two types of structural support - spicules that are spiny or pointy and made of calcium carbonate and springy spongin. Sponges we use around the house used to be made of sponges harvested from the ocean that were pounded to remove the spicules. Now, plastic sponges are commonly used.

There are three types of worms - Flatworms (Platyhelminthes), R0undworms (Nematodes), and Segmented Worms (Annelids).

Flatworms (Platy-hel- minthes) are flat and ribbon like, have bilateral symmetry and include things like tapeworms, planarians, flukes, and brightly colored marine flatworms. Marine flatworms have similar adaptations to nudibranchs (molluscs), but are flat and have no tufts. They are simple animals and are often parasites.

Roundworms (Nematodes) are ubiquitous and found commonly worldwide in every biome... but they are poorly understood because they are very very small. Less than 5cm. They have radial symmetry and often are parasites. Roundworms have scary looking mouths with teeth for attaching - often used in scary movies.

Segmented Worms (Annelids) include earth-worms, leeches, bristle-worms, and christmas tree worms. They are more advanced than the other worms with segments and body organs. They have radial symmetry and tunnel through their food.

For those of you studying invertebrates, you can use these matching cards to help!

Echinoderms

Echinoderm means spiny skin. Echinoderms include sea urchins, sea stars, sand dollars, sea cucumbers and some other odd organisms like feather stars and basket stars. All echinoderms have radial symmetry, spiny skin, and an endoskeleton called a test.

Most people are familiar with an orange sea star because on the east coast, that's all we've got. On the west coast and in other places around the world, it is easier to find a variety of sea stars in other colors and with different amounts of legs.

Sea stars have powerful tube feet that use water suction to open molluscs. When they eat molluscs, they actually stick their stomach into the shells of the mollusc, digest it, and then put their stomach.

Feather stars and basket stars both have crazy looking legs that they wave around to filter feed. Sea urchins and sand dollars are both covered with protective spines and eat with a scraping mouth called Aristotle's Lantern.

Sea cucumbers have lost most of their exoskeleton and are a bit squishier than other echinoderms. Sea cucumbers are important detritus eaters on the sea floor. When attacked by predators they will expel their guts as a meal for the predator as they make a get away. Sea cucumbers are able to regenerate these guts over time.

Crustaceans - Barnacles

If you look at a diagram, barnacles are like little shrimp glued on their backs with a white fence around them. They stick their feathery legs out to filter feed plankton. They are plankton for a while and once settled and glues onto a hard substrate never move again. This makes mating difficult, but the hermaphroditic barnacles have special talents. Gooseneck barnacles have a stalk that they attach to substrates with.

Crustaceans- Shrimp

SHRIMP - miniature lobsters... use their swimmerettes to keep themselves moving - most Americans have never seen one with its head and legs still attached!

• Gulf shrimp are the ones people most people are familiar with because these are the ones we eat!
• Shore shrimp live in sea grasses, are fairly small and clear, and are not commercially harvested because no one would make any money.
• Snapping shrimp (or pistol shrimp) have slightly larger claws and can use them to make sonic waves to stun their prey with sound. 
• Mantis shrimp whack their prey with arms that can unfold and strike lightning quick. 
• Cleaner shrimp make their living eating parasites off of fish and other sea creatures. 

One cool crustacean we have been learning about is the mantis shrimp. Mantis shrimp have folded claws like a praying mantis. They have lightning quick reflexes and shoot their arms out to smack their prey. It is said that they have enough power to break aquarium glass. If you want to see an interesting video of a mantis shrimp attacking and eating different prey - check here. 

Crustaceans - Crabs

CRABS - In general, you can tell the difference between boy crabs and girl crabs by looking at the shape of the plate on the abdomen. Boys have a thinner more pointy plate, girls have a wider more rounded plate because it is used to hold the egg mass. The mothers carry the eggs because not many predators will mess with them to get to the eggs.

• Blue Crabs are found in the Chesapeake Bay. They are very agressive, like to pinch, but are good to eat. They have a pointy-ended shell and swim fins. (you can kind of see the swim fins on the last leg of the crabs on the right)
• Spider Crabs have a rounder body shape, often a bumpy shell that will grow algae for camouflage, and longer more spindly legs. Spider Crabs include snow crabs and king crabs like the ones seen on Deadliest Catch. A decorator crab is a kind of spider crab that attaches stuff to its bumpy shell to blend in.
• Fiddler Crab males have one claw that is a lot bigger than the other. This is for impressing the ladies, and used to show dominance over other males. 
• Hermit Crabs have a weak exoskeleton and thus protect it with a stolen mollusc shell. They have adapted to this lifestyle and have modified back legs that hook on the inside to hold the shell on and one claw that is slightly larger to use as an operculum.

Crustacean Intro & Lobsters

Crustaceans have bilateral symmetry and a hard crunchy exoskeleton. Because the crustacean grows and the exoskeleton does not, crustaceans have to molt or shed their hard outercovering, exposing a new softer bigger covering that will harden in a few days.

LOBSTERS

There are two basic lobsters to be familiar with - the clawed lobster and the spiny lobster. Both are primarily scavengers. The clawed lobster has two different claws - a lighter faster shredder and a heavier more powerful crusher. The clawed lobster is more solitary because it is more aggressive. The spiny lobster does not have big claws, but can defend itself with its long whip like antennae. This lobster likes to congregate in groups and is not as aggressive. Both lobsters carry their eggs on the swimmerettes protecting them from potential predators.

Cephalopods

Today students explored the wonders of cephalopods. Cephalopod means head-foot and includes octopi, squid, cuttlefish, and the chambered nautilus.

Cephalopods are characterized by their large well developed eyes, numerous tentacles, a parrot like beak in the center of the tentacles, and well developed chromatophores in their skin that allow them to change color.

We watched numerous videos today to see and understand how and why cephalopods make ink clouds, to see how an octopus can swim with jet propulsion or use its tentacles to crawl around, and we also saw how a octopus can eat a shark!

For more information about cephalopods, check out CephBase and the Australian Cephalopod Research page.

Giant Squid

Students read a historical narrative about sea monsters and how those stories of the Kraken were based on squid sightings. We have known about the giant squid for several hundred years because of dead specimens and pieces found, but the first live one was not observed until 2005. Sailors used to think that the giant squid was much bigger because of a measurement error. Sucker marks on sperm whales were used to estimate size until they relaized that those marks and scars grew bigger as the whale grew.

Students then read a fictional account about a squid attacking the Jersey Shore (article pictured at left) and had to identify what parts of the stories were accurately portraying the squid and which parts were inaccurate.

Gastropods

Gastropod means "stomach foot" and includes all snails and anything else that makes one shell. Gastropods have one foot, one shell, and one siphon.

Some shells are spiral and have an operculum to act as a door for when they hide inside. The snail lives in the entire shell (all the way up into the top and retreats inside to hide when it feels threatened or exposed. The operculum blocks any would-be attackers and is made of a material similar to fingernails. These types of molluscs include whelks and moon snails.

Other shells are not spiral and the snail has good suction power so that predators have a difficult time pulling the snail off the rocks. These types of molluscs include slipper snails, abalones, and limpets.

Nudibranch (naked-gills) are sea slugs that have lost the ability to make a shell over evolutionary history. They are still classified as gastropods.

Even though they don't have a shell, they do however have some interesting adaptations to keep from getting eaten. Most nudibranch exhibit warning coloration because they are poisonous or have stingers - none that they make - they acquire them from the prey that they eat!

National Geographic did a great article a few years ago full of lovely photos. Both are linked here. Watch the video for a full-range spectrum of photos.

Slimy Slugs

Today classes got a close up look at the Limax maximus and their slimy mollusc bodies. Thank you Cassie for bringing in Professor Paulie Slops! Students looked at the two sets of tentacles (eyespots and sensory tentacles) and the hole the land slug breathes through. Some touched it to see what the slug felt like and quite a few third period students let the slug slime all over them. Way to be brave!

Slugs can be considered gross because of the copious amounts of mucus they leave behind. The mucus helps them get a better grip on surfaces and helps prevent dessication, drying out. It can also make the slug more difficult to pick up by predators. More information about slugs can be found here.

Pearls

Pearls can be made by any mollusc that has a shell. I passed around my pearls and some shells that I have with pearls on the sides - not all pearls are free floating - they can be attached to the side of a shell.

A mollusc makes a pearl to cover an irritating spot like a piece of sand that gets inside the shell. Pearls can be "glued" to the side of the shell or free to move inside the mollsucs shell. We prefer the "free" kind.

Here is a great short video that explains the process!

Any mollusk that produces a shell can produce a pearl. Nevertheless, naturally occurring pearls are rare, found in perhaps one of every 10,000 animals. The cultured pearl industry, which has flourished since the early 20th century, has developed techniques to greatly improve these odds. Indeed, more pearls are produced now than at any time in human history.( SOURCE This is a good website for lots of information on pearls)

Molluscs

Students are in the midst of Unit 4 Molluscs busily learning about the different classes of Molluscs and trying to learn a variety of sea shells. Students have learned the basics about sea shells

• The shells found on the beach are from dead organisms.
• Any mollusc that has a shell, makes it shell.
• Sea shells are made of calcium carbonate.
• Shells are smooth on the inside because slimy molluscs don't want to rub their soft bodies on something rough. If they are smooth on the outside, then the mollusc also wears its body on the outside of its shell.

Today's cool mollusc was the chiton, an odd mollusc that has 8 overlapping plates held together by its soft squishy mantle, and the plates come apart when the animal dies. Chitons are built like armored cars and have great suction to stay on the rocky coast in waves and storms. They spend their days sliming around scraping algae. When pulled off a rock, it can roll into a ball to protect its squishy parts. More info can be found here.

Students also learned the four major classes of bivalves - clams, mussels, oysters, and scallops. Bivalves have 2 shells and 2 siphons, as well as adductor muscles to help keep their shells from opening for hungry predators. Bivalves include some of the more well know shellfish like scallops, clams, oysters, and scallops as well as a few like jingles, ark shells, and cockles. Pictured to the right are a clam (tan), oyster (grey), and mussel (black).

Mussels make byssal threads for attaching (so do ark shells and jingle shells) and scallops have eyespots to see predators. Oysters make cement to stick together and clams have a powerful foot for digging down and hiding.

Weird Biomes

Students have been learning all the different biomes that exist in the oceans. Most people have heard of coral reefs and think about the beach, but there are actually many different biomes in the ocean.

One of the weirdest, but also most interesting is Whalefall. Whalefall is when a dead whale settles to the bottom of the ocean and organisms move in to feed on the carcass until even the bones are decomposed. Hagfish are a dominant scavenger as well as bacteria. It may not seem like a big deal, but this biome boasts over 160 species that are not found on the surrounding benthos. More info can be found at the link above, or here. Listen to a podcast here.

Deep sea benthos is another biome and it is pretty boring. Its a gooey squishy substrate populated by some dd scavengers, but there is not a high biodiversity and not a lot of food to eat.

Photic vs Aphotic is an odd one involving the light and dark zones of the ocean. Some organisms hide in the dark aphotic zone during the day and migrate up to the surface (the photic zone) at night to eat the phytoplankton. Predators also migrate to eat the things that are eating the phytoplankton.


Not all biomes are found at the bottom of the sea or in the dark. Along coasts you can find rocky coasts, sandy beaches, salt marshes, mangroves, sea grass beds, kelp forests, and fouling communities.

I think fouling communities are really interesting... because all these organisms need is a hard substrate (surface) to stick on. This could be a dock, a pier, a boat, or anything that's in the water long enough. Most people have seen all the 'stuff' growing on the pole legs of piers and docks, but don't really think of the variety of organisms that grow there - or their importance. Most of these organisms are filter feeders and do a lot for water quality. They also break down the surfaces like scavengers... not something we want for our boats and docks we use, but important nonetheless.

There is a lot of information to learn this unit. Students will be given two review sheets one general, one biome specific. The Unit 3 Test is one of the hardest of the year, and it is coming soon!

Beginning Biomes

Students have been learning all the different biomes that exist in the oceans. Most people have heard of coral reefs and think about the beach, but there are actually many different biomes in the ocean.  On the East Coast right here in Virginia, we can find salt marshes, sea grasses, sandy beaches, and maritime forests. In Florida you can find mangroves (trees that grow in salt water) and coral reefs. On the west coast, rocky coasts and kelp forests are the two dominant biomes.

 Along some coasts you can find rocky coasts, sandy beaches, salt marshes, mangroves, sea grass beds, kelp forests, and fouling communities.  Kelp forests are dominated by kelp that can grow to 300 feet tall. The kelp is held near the surface by lots of air bladders. Kelp forests are important because they provide a lot of substrate and habitat for organisms to live, hide and eat.

We also discussed sea grass beds. Sea grass is super-important for stabilizing the substrate and holding the sand down. This promotes water clarity and decreases turbidity. Nothing eats sea grass when it is alive except for manatees. Everything else eats it after the bacteria have decomposed it a bit.

Salt Marshes are one of the most productive ecosystems, but nothing eats the salt marsh grass when its alive... once the anaerobic bacteria break it down into black mush, then other organisms eat it. 

Mangroves are trees that can grow in salt water. They have crazy prop roots or finger like roots called pneu- mato- phores that stick up out of the water so the tree can get oxygen during high tide. The roots provide a lot of substrate that a lot of fouling organisms will colonize and use as habitat.

 There is a lot of information to learn this unit. The Unit 3 Test is one of the hardest of the year.

Zonation

Today we discussed zonation in Marine Ecology. Zonation happens when organisms are adapted to a very specific set of conditions. Because some organisms are better adapted to these certain conditions, we see bands of organisms occupying zones. Today we talked about zonation and specifically how it affects the rocky coastline.

Students identified zones on rocky coast pictures and took notes on the material. Here is an example of a photo where the zones can clearly be seen by changes in dominant seaweeds. The yellow layer is the upper zone and the white pink is the middle zone. It is easy to see the high water mark or where the high tide will reach. You can also see the lichens in the spray zone.

The spray zone is one of the hardest areas to live in because of the huge changes in salinity and temperature.

We also talked about tide pools. Tide pools are depressions that trap water when the tide recedes. You can find all kinds of things in tide pools, but tide pools in the lower zone have a higher biodiversity than tidepools found in the upper zone. This is because they are more often "refreshed" with water that keeps salinity, dissolved oxygen, and the temperature stable, as well as add nutrients and more food! Here is a neat article from National Geographic about tidepools (and where this photo is from). 

Seaweeds

Students learned about the three types of seaweed. Seaweed and algae are the same thing and they are classified by pigment type - red, brown, or green. 

Red seaweeds are the most common, but we don't see a lot of them because they like tropical waters and deep waters. 

Brown algae is the most common seaweed on our coast, whereas green algae is the most common in the freshwater of Virginia.

There is also cyanobacteria - or the blue green algae which we discussed during the plankton part of the unit. 

Some algae is calcareous - meaning it stores calcium carbonate in its tissues. This makes it crunchy and deters herbivores. The most common is a calcareous red algae that makes a pink crust on just about everything left in the ocean.

A lot of seaweed has air bladders to help it float towards the surface.  Air bladders ensure adequate sunlight for photosynthesis. Other important adaptations include flexibility and gels to stay hydrated when the tide goes out. Students observed samples of dried seaweed.