Chapter 14: Animals of the Pelagic Environment; vocab and questions

lunger

Fish (such as grouper) that sit motionless on the ocean floor waiting for prey to appear. A lunger uses quick bursts of speed over short distances to capture prey.

Describe several different types of microscopic and macroscopic zooplankton.

Krill - in the subphylum Crustacea and resemble minishrimp or large copepodsCnidarians - formerly known as coelenterates have soft body more than 95% water and tentacles armed with stinging cells called nematocystsHydrozoan - have gas chambers called pneumatophores which serve as floats and sails that allow the wind to push them across the ocean surfaceScyphozoan (or jellyfish) - have a bell-shaped body with a fringe of tentacles and a mouth at the end of the clapper-like extension hanging beneath the bell-shaped float

What are the five basic shapes of caudal fins, and what are their uses?

Most active swimming fish have two sets of paired fins used in maneuvers such as turning, braking, and balancing. These are the pelvic fins and pectoral fins (refer to Figure 14.9). When not in use, these fins can be folded against the body. Vertical fins, both dorsal and anal, serve primarily as stabilizers. The fin that provides most of the thrust for forward motion in high-speed fish is the caudal fin (tail fin).Most active swimming fish have two sets of paired fins used in maneuvers such as turning, braking, and balancing. These are the pelvic fins and pectoral fins (refer to Figure 14.9). When not in use, these fins can be folded against the body. Vertical fins, both dorsal and anal, serve primarily as stabilizers. The fin that provides most of the thrust for forward motion in high-speed fish is the caudal fin (tail fin).

Are most fast-swimming fish cold-blooded or warm-blooded? What advantage does this provide?

Most fast-swimming fish, such as mackerel, sharks, and tuna, are warm-blooded (homeothermic). The higher body temperature of homeothermic cruisers increases the power output of their muscle tissue. Therefore they can move faster more immediately than cold-blooded fish. These homeothermic fish conserve the heat needed to maintain body temperature by a modification of their circulatory system: they have cutaneous veins and arteries running along the sides of their body.

How can dolphins be differentiated from porpoises?

Porpoises are generally smaller than dolphins, and they have a more "stout" (bulky and robust) body shape compared to the elongated and streamlined dolphin body. Generally, porpoises have a blunt snout (called a rostrum) in contrast to dolphins, which have a longer rostrum. Porpoises have a smaller and more triangular (or, on one species, no) dorsal fin, whereas the dolphin's dorsal fin is sickle-shaped or falcate. The best way to tell the two apart is by their teeth. Dolphin teeth end in points in contrast to porpoise teeth that are blunt or flat (shovel-shaped) and resemble human incisors.

How can true seals be differentiated from the eared seals (sea lions and fur seals)?

Seals lack the prominent earflap that is specific to sea lions and fur.• Seals have smaller and less prominent front flippers (called fore flippers) than sea lions and fur seals.• Seals have prominent claws that extend from their flippers that sea lions and fur seals lack.• Seals have a different hip structure than sea lions and fur seals. Seals cannot move their rear flippers underneath their bodies as sea lions and fur seals can.

krill

young fry fish, resemble mini shrimp or large copepods

myoglobin

a red pigment with an affinity for oxygen

cruisers

actively seek prey, less than half of a cruiser's muscle tissue is mostly red, ex: tuna

heterocercal fins

asymmetrical, with most of their mass and surface area in the upper lobe

cold blooded/poikilothermic

body temperatures are nearly the same as their environment, usually these fish are not fast swimmers

counterillumination

camouflaging by using belly lights to match the color and intensity of dim filtered sunlight from above and obliterate a telltale shadow

warmblooded/homeothermic

can maintain a body temperature regardless of the water temperature

rounded fins

flexible and useful in accelerating and maneuvering at slow speeds

lunate fins

found on fast-cruising fish ex: tuna, marlin, swordfish the fins are rigid and useless for maneuverability but very efficient for propulsion

truncate fins/forked fins

found on faster fish, the fins are somewhat flexible for better propulsion but are also used for maneuvering

cnidarians

have soft bodies that are more than 95% water and tentacles armed with stinging cells

deep-sea fish

have special adaptations to efficiently find and collect food, they have good sensory devices that detect movement

scyphozoan

jellies

photophores

light-producing organs, which can simple luminous spots or may be quite complex and equipped with lenses, shutters, color filters, reflectors

test

microscopic forms of zooplankton's hard shell

copepods

microscopic shrimplike animals of the subphylum Crustacea which also includes shrimps, crabs, and lobsters

foraminifers

microscopic to barely macroscopic single-celled protozoans

Describe the mechanism by which bioluminescence is accomplished in deep-sea organisms. What is bioluminescence useful for in the marine environment?

About 80% of bioluminescent organisms have light-producing organs called photophores. Light may be produced from substances that form during digestion, from specialized cells, or from symbiotic bacteria. A biological pigment called luciferin emits photons, which are packets of light, when oxygen is present or produced. Bioluminescence is useful for finding food or attracting prey, marking territory, communication, confusing predators, avoiding predators with distraction, or camouflage by using belly lights to simulate sunlight from above.

Discuss how sound reaches the inner ear of toothed whales.

All cetaceans have evolved structures that insulate the inner ear housing from the rest of the skull. In toothed whales, the inner ear is separated from the rest of the skull and surrounded by an extensive system of air sinuses (cavities). The sinuses are filled with an insulating emulsion of oil, mucous, and air, and are surrounded by fibrous connective tissue and venous networks. In many toothed whales, it is believed that sound is picked up by the thin, flaring jawbone and passed to the inner ear via the connecting oil-filled body.

myoglobin

An oxygen-storing, pigmented protein in muscle cells.

Discuss why the rigid gas chamber in cephalopods limits the depth to which they can descend. Why do fish with a swim bladder not have this limitation?

Because the pressure in their air chambers is always one kilometer per square centimeter, cephalopods must stay above a depth of approximately 500 meters to prevent collapse of its chambered shell. A change in depth either expands or contracts the swim bladder, so fish must add or remove gas to maintain a constant volume.

What are the three types of symbiosis, and how do they differ?

Commensalism occurs when a smaller or less-dominant participant benefits without harm to the host species that provides the commensal with food or protection. Mutualism occurs when both species benefit. Parasitism occurs when one organism (parasite) benefits at the expense of the host organism.

Discuss reasons why gray whales leave their cold-water feeding grounds during the winter season.

Gray whales are highly adaptable. Because they migrate to warm water nursery lagoons in the winter, and then to cold water Arctic feeding grounds in the summer, they are able to tolerate wide ranges in both water and air temperature.

What are several benefits of schooling? What other adaptations do pelagic animals possess to avoid being prey?

If members of a species form schools, they reduce the percentage of ocean volume in which a cruising predator might find one of their species.• Should a predator encounter a large school, it is less likely to consume the entire unit than if it encounters a small school or an individual.• The school may appear as a single large and dangerous opponent to the potential predator and prevent some attacks.These adaptations include using speed, secreting poisons, and mimicking other poisonous or distasteful species. Some species use transparency, camouflage, or countershading.

Describe the process by which the sperm whale produces echolocation clicks.

In the sperm whale's large head, air is forced from the trachea through the nasal passages and past the lips of the "monkey's muzzle." Contractions of muscles in these structures produce sound that travels toward the head and reflects off the front of the skull, which is bowl-shaped and resembles a radar dish. The sound passes through an organ called the spermaceti organ, in which sound is concentrated by forming various shapes and sizes of lenses. In essence, the organ acts as an acoustical lens that focuses the sound.

Describe marine mammals within the Order Carnivora, including their adaptations for living in the marine environment.

Marine mammals within the Order Carnivora include sea otters, polar bears, and the pinnipeds (walruses, seals, sea lions, and fur seals), all of which have prominent canine teeth. Sea otters have dense fur that insulates them from the cold water in which they live. Polar bears have fur with hollow hair shafts for insulation and webbed feet for swimming. Pinnipeds have sensitive whiskers and prominent skin-covered flippers that are used to propel them through the water.

Describe the marine mammals within the Order Sirenia, including their distinguishing characteristics.

Marine representatives of the Order Sirenia include the manatees and dugongs, which are collectively referred to as "sea cows." The manatees are concentrated in coastal areas of the tropical Atlantic Ocean, while dugongs populate the tropical regions of the Indian and Western Pacific Oceans. Both of these animals have a paddle-like tail and rounded front flippers. The land-dwelling ancestors of the sirenians were elephant-like, and extant sirenians today retain some of these unique characteristics, such as a large body size and the presence of toenails in manatees. The sirenians have sparse hairs covering their body but concentrated around the mouth.

lungers

sit and wait for prey to come close by, have truncate caudal fins for speed and maneuverability and almost all their muscle tissue is white, ex: grouper

What do fish use their fins for?

swimming and staying afloat within the water column

Describe the differences between cetaceans of the Suborder Odontoceti (toothed whales) from those of the Suborder Mysticeti (baleen whales). Be sure to include examples from each suborder.

Suborder Odontoceti (toothed whales) have prominent teeth and includes killer whales, sperm whales, porpoises, and dolphins. Suborder Mysticeti (baleen whales) includes the great whales (the largest whales) such as the blue whale, the finback whale, humpback whale, and the gray whale. The baleen whales have no teeth. Instead they have baleen, plates of fibrous material that hang from the whale's upper jaw on the inside of their mouths. Toothed whales have one external nasal opening (blowhole) in contrast to the baleen whales that have two external openings.

Why did the International Whaling Commission (IWC) invoke a ban on commercial whaling?

The International Whaling Commission (IWC) was established by the UN in 1946 to manage whale populations and prevent further depletion of whale populations which are at critically low levels.

What fin can provide the most thrust

the caudal (tail) fin, which can have a variety of shapes, depending on the lifestyle of the fish

What are the two food sources of deep-water nekton? List several adaptations of deep-water nekton that allow them to survive in their environment.

The food source for deep-water nekton comes from one of two places: detritus, dead and decaying organic matter and waste products that slowly settle through the water column from the highly productive surface waters, or each other. There are a number of predatory species.Deep-water nekton have many special adaptations to allow them to be efficient at finding and collecting food. These include:• Good sensory devices such as long antennae or sensitive lateral lines that are used to detect the movement of other organisms within the water column.• Many species have large and sensitive eyes that enable them to see potential prey. To avoid becoming prey, most species are dark colored so that they blend in with the environment.• Other species are blind and rely on their other senses to obtain food. For instance, the sense of smell is well developed in some species, and that allows certain fish to track down prey items by following a scent trail.• Well over half of deep-sea fish have bioluminescence capabilities (the ability to biochemically produce light) by using specially designed structures or cells called photophores.• Large sharp teeth.• Expandable bodies.• Hinged jaws that can disarticulate.• Huge mouths in proportion to their body size.

Describe the mechanism by which baleen whales feed.

The main obstacle that baleen whales face in obtaining food is how to concentrate their small prey items and how to separate these items from seawater. To accomplish these tasks, baleen whales use their rows of fibrous baleen in their mouths that hang from their upper jaw and act as an ideal strainer. To feed, baleen whales fill their mouths with water that includes their prey, allowing their pleated lower jaw to balloon in size. The whales force the water out between the baleen slats, trapping small fish, krill, and other plankton on the inside of their mouths. Mostly, baleen whales feed at or near the surface, sometimes working cooperatively in large groups. However, the gray whale has short baleen slats and feeds by filtering sediment from the shallow bottom of its North Pacific and Arctic feeding grounds, straining out a diet of benthic organisms.

What common characteristics do all organisms in the Class Mammalia share?

They are warm-blooded.2. They breathe air.3. They have hair (or fur) in at least some stage of their development.4. They bear live young (except for the few egg-laying Australian mammals from the Subclass Prototheria, which includes the duck-billed platypus and the spiny anteater).5. The females of each species have mammary glands, structures that give the class its name, that are used to produce milk for their young.

symbiosis

occurs when two or more organisms associate in a way that benefits at least one of them

biomass

pelagic organisms comprise the vast majority

hydrozoan

represented by the portuguese man-of-war, their gas chambers serve as floats and sails that allow the wind to push them across the ocean surface

gray whale

short coarse baleen, no dorsal fin, only two to five ventral grooves on its lower jaw, in the baleen whale family

radiolarians

single-celled, microscopic protozoans that build their hard shells out of silica