Chapter 7.1

Question 1

What are the two major types of animals?

Answer 1

–vertebrates and the invertebrates.

• Vertebrates are animals that possess a backbone (a row of bones called vertebrae),
• and invertebrates are animals without backbones.

Question 2

Compare the abundance of invertebrate vs. vertebrate animal species.

Answer 2

• At least 97% of all species of animals are invertebrates.

- All major groups of invertebrates have marine representatives, and many are exclusively marine.

Question 3

Name the eight phyla of invertebrates about which you are responsible for learning in this unit. List at least one representative type of organism from each phylum.

Answer 3

Phylum Porifera: the sponges
Phylum Cnidaria: the sea anemones, jellies, corals, and their relatives
Phylum Ctenophora: the comb jellies
Phylum Platyhelminthes: the flatworms
Phylum Nemertea: the ribbon worms
Phylum Nematoda: the roundworms
Phylum Annelida: the segmented worms (earthworms)
Phylum Mollusca: snails, clams, octopus, squid, chitons

Question 4

Generally describe sponges, including their level of organization, body plan and symmetry, and life styles.

Answer 4

• Phylum Porifera, which means “pore bearers.”
  –structurally simplest of the invertebrates and are complex aggregations of specialized cells.
  -They have a cellular level of organization.
  -They do not have tissues, organs, or organ systems.
• relatively simple body plan and no symmetry.
  -Water enters the sponge through tiny pores or ostia and circulates through a series of canals where plankton and organic particles are filtered out and eaten.
  -The network of canals and relatively flexible skeletal framework give sponges their “spongy” texture.
  -Nearly all sponges are sessile and live attached to the bottom (or any surface).

Question 5

REVIEW: What are tissues? What are organs? What are organ systems?

Answer 5

-Tissues are specialized, coordinated groups of cells in an organism.
-Organs are structures consisting of several types of tissues, grouped together to carry out particular functions.
-Organ systems are groups of organs that work together to perform a particular function in an organism.

Question 6

What is suspension feeding?

Answer 6

Suspension feeding is a feeding style in which animals eat food particles suspended in the water.

Question 7

What are filter feeders?

Answer 7

Organisms that actively filter food particles from the water by pumping water through their bodies or using filtering structures to sweep up food particles are known as filter feeders.

Question 8

What is passive feeding suspension?

Answer 8

Passive suspension feeding occurs when water is not actively pumped (but passively flows by the animal) and the animal uses cilia and mucus to move food particles to the mouth.

Question 9

Define the terms sessile and mobile.

Answer 9

Sessile refers to organisms that live attached to the bottom or a surface. Generally, these organisms are not mobile (they can’t move).

Question 10

Briefly describe how sponges feed, using collar cells and oscula.

Answer 10

• The outer surface of a sponge is covered with pores, through which water is pumped into feeding chambers that are lined with special feeding cells called collar cells.
• Collar cells have flagella that create currents and a thin collar that traps food particles, which are then ingested.
• Water leaves the sponge though a large openings called oscula

Question 11

Describe the structural support of sponges.

Answer 11

• Most sponges have spicules, which are supporting structures of different shapes and sizes that are embedded in a gelatinous layer between the outer and inner layers of cells in the sponge.
• Spicules may be siliceous or calcareous.
• Many sponges also have tough, elastic fibers made up of the protein spongin for support.

Question 12

What is siliceous? What is calcareous?

Answer 12

-Siliceous is an adjective that refers to things made up of silica (SiO2).
-Calcareous is an adjective that refers to things made up of calcium carbonate (CaCO3).

Question 13

Describe reproduction in sponges.

Answer 13

• reproduce both sexually and asexually.
• Asexual reproduction occurs when branches or buds break off of the parent sponge and grow into separate sponges that are identical to the parent.
• Sexual reproduction occurs when special collar cells in a sponge develop into male (sperm) and female (egg) gametes.
• The male gametes are typically released in to the water—this is called spawning.
• The sperm are drawn into the sponge, which is where fertilization takes place and the early stages of development take place.
• Eventually a planktonic larva is released by the sponge and drifts in the water until it settles on the bottom and grows into a new sponge.

Question 14

What is metamorphosis?

Answer 14

-Metamorphosis refers to the dramatic change in body style and/or life style from the larval to adult stages of a marine organism.

Question 15

Briefly describe the diversity of types of sponges in the ocean.

Answer 15

• Almost all of the 9,000 species of sponges are marine.
• can be found in shallow and deep water, tropical and polar water, and everything in between.
• may be branching, tubular, round, volcano-like, and any other shape.
  -Encrusting sponges form thin, sometimes brightly colored growths on rocks or other hard surfaces. –Glass sponges live in deep water and have a lace-like skeleton of fused siliceous spicules.
• Boring sponges create thin channels through calcium carbonate, such as oyster shells and corals, in which they live.
• Coralline sponges have a calcium carbonate skeleton beneath the body of the sponge and may also have siliceous spicules and spongin.

Question 16

Describe the economic significance of sponges.

Answer 16

• Bath sponges are of limited commercial importance—they are the spongin fibers remaining after cells and debris are washed away.
• Some sponges produce chemicals that are potentially of medicinal importance.

Question 17

Generally describe cnidarians, including their level of organization, body shapes and symmetry, and life styles.

Answer 17

• include sea anemones, jellies, and corals.
• have a tissue level of organization and are radially symmetrical.
  -have two basic forms: polyp and medusa.
  -A polyp is a sac-like attached stage, and a medusa is a bell-like, upside down polyp adapted for swimming.
  -Cnidarians may spend part of their life history as a medusa and part as a polyp;
  some cnidarians are only one or the other for their entire lives.

Question 18

See Fill-In Charts

Answer 18

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Question 19

Describe radial symmetry.

Answer 19

• Organisms with radial symmetry have similar parts of the body arranged and repeated around a central axis
• they look the same from all sides and have no head, front, or back.
• They do have an oral surface, where the mouth is, and an aboral surface on the opposite side.

Question 20

Describe the cnidarian body plan.

Answer 20

• Both polyp and medusa forms of cnidarians have a similar body plan.
• There is a centrally located mouth that is surrounded by tentacles, which are used to get food.
• The mouth opens into a blind gut where digestion occurs.
• The blind gut has only one opening—the mouth—and wastes are spit out from the mouth.
• Cnidarian tentacles are armed with nematocysts, which are stinging structures used to capture small prey.
• Cnidarian are carnivores.
• Cnidarians have two layers of cells—an inner gastrodermis that lines the gut and an outer epidermis.
• The mesoglea is the layer between these two cell layers; in the jellies it is expanded and gelatinous.

Question 21

What are the three classes in the Phylum Cnidaria about which you are responsible for learning?

Answer 21

Class Hydrozoa, Class Scyphozoa, and Class Anthozoa.

Question 22

Generally describe the Class Hydrozoa, including the general body plan of its members.

Answer 22

• Hydrozoans have a wide range of forms and life histories.
• Many are feathery or bushy colonies of tiny polyps. -They typically produce planktonic gametes and larvae.
• The larvae settle on the bottom to produce a new colony of hydrozoans.

Question 23

Name and describe at least one representative type of hydrozoan.

Answer 23

• Siphonophores are drifting colonies of hydrozoan polyps.
• Often, some of the polyps are specialized as gas-filled floats that buoy the entire colony.
• Other polyps are specialized tentacles for capturing food.

Question 24

Generally describe the Class Scyphozoa, including the general body plan of its members, and name at least one representative type of scyphozoan.

Answer 24

-Scyphozoans include the common larger jellies in the ocean.
-The medusa is the dominant stage of scyphozoans.
-The rounded body or bell of jellies is contracted rhythmically to aid jellies in swimming.
-their swimming abilities are weak, and currents easily move them.
-As a result they are considered to be part of the zooplankton—the heterotrophic plankton.
The nematocysts of scyphozoans can give extremely painful and sometimes fatal stings.

Question 25

Name and describe at least one representative type of scyphozoans.

Answer 25

Sea nettle

Question 26

Generally describe the Class Anthozoa, including the general body plan of its members, and name and describe at least one representative type of anthozoan.

Answer 26

• anthozoans are solitary or colonial polyps that lack a medusa stage and have more complex polyps than do the hydrozoans or scyphozoans.
• Most cnidarians are anthozoans.
• Anthozoans occur in a variety of sizes, shapes, and types.
  -Some are fleshy and do not have a hard skeleton: -Sea anemones are common and colorful “fleshy” anthozoans that may be solitary or colonial.
• Soft corals, sea pens, and sea pansies are colonial “fleshy” anthozoans.
  -Several types of anthozoans secrete hard skeletons: Colonial stony corals secrete calcium carbonate skeletons that may form coral reefs in tropical waters.
• Gorgonians, such as sea fans are colonial anthozoans that secrete a protein, branching skeleton.

Question 27

Briefly describe feeding and digestion in cnidarians.

Answer 27

• most cnidarians are carnivores and use their nematocysts to capture prey.
• Nematocysts are a fluid-filled capsule that contains a thread that can be quickly ejected.
• The thread may be sticky or armed with spines.
• Some nematocysts contain toxins (which is why they “sting”).
• when the nematocysts are touched (by prey or by an unsuspecting swimmer), they shoot out the thread, which sticks to the prey.
• They then “reel” the prey into the tentacles and then the mouth.
• Food passes into the gut where it is digested.

Question 28

Briefly describe the tissues of cnidarians.

Answer 28

• Cnidarians lack organ systems, so they don’t have a true nervous system with a brain or nerves.
• they do have specialized nerve cells that connect together to form a nerve net.
• This relatively simple nerve net can distinguish between prey and other cnidarians.
• Some medusae have primitive eyes, and they also have statocysts—small calcareous “stones” in fluid-filled chambers surrounded by sensitive hairs.
• These allow medusae to distinguish “up” from “down.”

Question 29

Generally describe comb jellies, including their level of organization, body plan and symmetry, and life styles.

Answer 29

• Comb jellies are in Phylum Ctenophora and are exclusively marine.
• Ctenophores have a tissue level of organization.
• They are radially symmetrical and have gelatinous bodies that resemble medusae.
• Eight rows of ciliary combs, long cilia fused at the base like combs, beat in waves and are used in swimming.
• Comb jellies species vary in size from a few millimeters to several feet in length.
  -Comb jellies are common carnivores of plankton in surface waters of the ocean. They often occur in swarms.
• They capture their prey using two long tentacles armed with sticky cells named colloblasts.
• Comb jellies lack nematocysts.

Question 30

What is bilateral symmetry? What are its advantages and disadvantages compared to radial symmetry?

Answer 30

• Bilateral symmetry is the arrangement of body parts in such a way that there is only one way to cut the body and get two identical halves.
• Bilaterally symmetrical animals have a front or anterior end and a rear or posterior end.
• At the anterior end is a head with a brain (or at least a collection of nerve cells).
• Bilaterally symmetrical organisms also have dorsal or back surface that is different front the front or ventral surface.
  -Radial symmetry works well for organisms that drift in currents or are attached to surfaces.
• Animals that are more active and crawl or swim in one direction tend to be bilaterally symmetrical
• Bilaterally symmetrical animals tend to have more sophisticated behaviors than those of radially symmetrical animal (because they have more highly developed nervous systems].

Question 31

Generally describe flatworms, including their level of organization, body shape and symmetry, and life styles.

Answer 31

• Flatworms are in the Phylum Platyhelminthes, are bilaterally symmetrical, and are noted for their dorsoventrally flattened shapes.
• Flatworms are the simplest animals in which tissues are organized in to organs and organ systems.

Question 32

Name the most commonly seen type of marine flatworms.

Answer 32

• There are approximately 20,000 species of flatworms, and the most commonly seen marine flatworms are the turbellarians.
• Turbellarians are free-living carnivores that often have striking color patterns
• Other types of flatworms include the parasitic flukes or trematodes and the parasitic tapeworms or cestodes.

Question 33

Briefly describe the organ systems of flatworms.

Answer 33

• Flatworms have a central nervous system in which information is stored and processed.
• In flatworms it typically consists of a simple brain, which is an aggregation of nerve cells in the head.
• There are also nerve cords that run the length of the body.
• The nervous system coordinates the muscular system and, therefore, motion.
• The flatworms have a blind gut, similar to cnidarians and ctenophores. -They also have a middle tissue layer called the mesoderm, which gives rise to the muscles, reproductive system, and other organs.

Question 34

Generally describe ribbon worms, including their level of organization, body shape and symmetry, and life styles.

Answer 34

-Ribbon worms are in the Phylum Nemertea and are more complex in their organization than the flatworms.
-They are long, thin worms that are carnivores and eat worms and crustaceans.
-They have bilateral symmetry and an organ system level of organization.
-Almost all the species of ribbon worms are marine.
They are found in all oceans and are more common in shallow water than in deep water.
-They range from several inches to many feet in length. Some are very brightly colored.

Question 35

Briefly describe the organ systems of ribbon worms.

Answer 35

• ribbon worms have a complete digestive tract, with a gut that includes a mouth and an anus.
• they have a circulatory system that transports blood with nutrients and oxygen to the tissues.
  -Ribbons worms have a very distinctive proboscis, which is a long, fleshy tube used to entangle prey.

Question 36

Generally describe nematodes, including their level of organization, body shape and symmetry, and life styles.

Answer 36

• Nematodes are in the Phylum Nematoda.
• They are bilaterally symmetrical and have an organ system level of organization.
• Some nematodes are known as roundworms, because they are small, slender, and cylindrical in shape.
• Nematodes are rarely seen but they are very, very common in sediments, where they feed on bacteria and organic matter.
• Many other nematodes are parasites—some of which can be passed on to humans when they are consumed along with their host fish.

Question 37

Briefly describe the organ systems and bodies of nematode worms.

Answer 37

• Nematodes pretty much have the full complement of organ systems: central nervous system, muscular system, digestive system, etc.
• They have a hydrostatic skeleton, which is a system that uses water pressure against the body wall to maintain body shape and to aid in locomotion.

Question 38

Generally describe segmented worms, including their level of organization, body shape and symmetry, and life styles.

Answer 38

• Segmented worms are in the Phylum Annelida
• They are bilaterally symmetrical and have an organ system level of organization.
• Their body consists of a series of similar compartments or segments, a condition known as segmentation
• The gut goes through all of the segments and lies in a cavity that is lined with tissue from the mesoderm and which is filled with fluid.
• This cavity, called the coelom, allows the segments to act as a hydrostatic skeleton.
• Segmented worms are very flexible because of their segments and are efficient crawlers and burrowers.

Question 39

Generally describe the Class Polychaeta, including the general body plan of its members, and name at least one representative type of polychaete.

Answer 39

• Almost all marine annelids are in the Class Polychaeta.
• Each segment of a polychaete has a pair of flattened extensions, called parapodia, which contain stiff and sometime sharp bristles or setae.
  -Polychaete worms are typically 2 to 4 inches long.
• They have a variety of life styles and habitats.
• Some crawl on the bottom, others burrow into the sediment, while others live in tubes that they construct.
• Some are even planktonic.
• Many crawling polychaetes are carnivores.
• Tube-dwelling polychaetes are usually passive suspension feeders.
• Burrowing polychaetes often are deposit feeders—they ingest soft sediment, extract the organic matter in it, and then expel the indigestible part.

Question 40

Fill-In Worm Body Plan

Answer 40

D

Question 41

Name at least one representative type of polychaete.

Answer 41

The fireworm is a carnivorous polychaete worm that is well known for the causing irritation to human skin when it is touched (its setae break off and embed themselves in our skin).

Question 42

Briefly describe the organ systems and bodies of polychaete worms.

Answer 42

• Polychaete worms have a closed circulatory system with the circulating blood in distinct blood vessels.
• To bring enough oxygen into the body, polychaete worms cannot rely on simple diffusion across their surface.
• Instead they have gills on the parapodia that have many small blood vessels, called capillaries, which allow for the easy absorption of oxygen and release of carbon dioxide.

Question 43

Generally describe molluscs, including their level of organization, symmetry, and life styles.

Answer 43

• Molluscs are members of the Phylum Mollusca, a very common and diverse group of organisms in the marine environment.
• Molluscs are bilaterally symmetrical and have an organ system level of organization.
• They exhibit a variety of life styles, including carnivores, herbivores, filter feeders, and scavengers.

Question 44

Describe the typical molluscan body plan.

Answer 44

-The typical body plan of molluscs includes a soft body with a calcium carbonate shell.
-The soft body is covered by a mantle, which is a thin layer of tissue that secretes the shell.
-The body is unsegmented.
-There is a ventral, muscular foot that is typically used for locomotion.
-Most molluscs have a head with eyes and other sensory organs.
- unique feature of molluscs is the radula, a tongue-like ribbon of small teeth that is used in feeding.
The radula is made up of chitin, a highly resistant carbohydrate. Gas exchange is through paired gills.
-Although all molluscs have this basic body plan, it is often greatly modified.

Question 45

Fill in mollusca body plan

Answer 45

G

Question 46

What are the four classes in the Phylum Mollusca about which you are responsible for learning?

Answer 46

• Class Gastropoda (the snails),
• the Class Bivalvia (the clams),
• the Class Cephalopoda (the squid and octopuses),
• the Class Polyplacophora (the chitons).

Question 47

Generally describe the Class Gastropoda, including the general body plan of its members and their life styles.

Answer 47

• includes the familiar snails as well as some organisms that may not be as familiar, such as the nudibranchs or sea slugs, limpets, and abalone.
• This class is the largest, most common, and most varied group of molluscs.
• A typical gastropod has a coiled mass of vital organs enclosed by a dorsal, coiled shell.
• The shell rests on a central creeping foot.
  -Most gastropods use their radula to scrape algae from rocks—they are herbivores;
• However, many gastropods are predators, often feeding on other molluscs.
• Most are benthic, but some are planktonic.

Question 48

What is benthic?

Answer 48

Benthic is an adjective used to describe organisms that live on the bottom, either on or within the bottom sediments.

Question 49

Describe nudibranchs. What is their common name?

Answer 49

• Nudibranchs or sea slugs are gastropods with no shell.
• Colorful branches of the gut or exposed gills make sea slugs some of the most beautiful of all marine organisms.
• Sea slugs are all predators, feeding on sponges, hydroids, and other invertebrates.
• As a defensive mechanism, nudibranchs often retain noxious chemicals or undischarged nematocysts taken undigested from their prey.

Question 50

Generally describe the Class Bivalvia, including the general body plan of its members and their life styles.

Answer 50

• The Class Bivalvia includes familiar molluscs, such as clams, mussels, oysters, and similar organisms.
• Bivalves retain the basic molluscan body plan in a modified form—the body is laterally compressed and enclosed in a shell.
• The shell has two parts—each called a valve.
• There is no head and no radula.
• The gills are used not only for respiration but also to filter food particles from the water.
• Bivalves are filter feeders.
• The inner surface of the shell is lined by the mantle, so that the whole body lies in the mantle cavity.
  -Many bivalves burrow into sand or mud and draw water in and out of the mantle cavity through siphons formed by the edges of the mantle.
• Some bivalves live attached to hard surfaces.
• Some of the more unusual life styles of bivalves include that of the scallops, which are weak swimmers, and of the shipworms, which are bivalves that bore into soft wood

Question 51

Generally describe the Class Cephalopoda, including the general body plan of its members and their life styles.

Answer 51

• includes the octopuses and squid.
• These are voracious predators specialized for locomotion.
• They have adapted the molluscan body plan to facilitate this active life style.
• They have complex nervous systems and have either a greatly reduced or no shell.
• The foot is modified into arms and tentacles, usually equipped with suckers to capture prey.
• They have large eyes, set on either side of their heads, which are remarkably complex.
• The body is rounded in octopuses and elongated in squid.
• It is protected by a thick and muscular mantle.
• Water enters through the mantle and leaves through the siphon or funnel, a muscular tube formed by the foot.
• Cephalopods swim by forcing water out of the mantle cavity through the siphon—a type of jet propulsion.
• They can distract potential predators by emitting a dark fluid produced by the ink sac.

Question 52

Briefly describe octopuses.

Answer 52

• have eight long arms and lack a shell.
• They are benthic hunters that specialize on crustaceans such as crabs, lobsters, and shrimp, as well as other molluscs.
• They bite their prey with a pair of beak-like jaws.
• Some octopuses secrete a paralyzing toxin, but most are harmless

Question 53

Fill in octopus chart

Answer 53

G

Question 54

Briefly describe squid.

Answer 54

• better swimmers than are octopuses, and they can move in all directions as well as remain motionless in one place.
• They have eight arms and two tentacles, all armed with suckers.
• They have a greatly reduced shell.

Question 55

Generally describe the Class Polyplacophora, including the general body plan of its members and their life styles.

Answer 55

• includes the chitons.
• They have eight overlapping plates that make up their shells.
• Their internal organs are not coiled, as in gastropods.
• Most live on rocky shores, where they use their radula to scrape algae—they are herbivores.

Question 56

Generally describe feeding and digestion in molluscs.

Answer 56

• Molluscs have complete digestive tracts.
• digestive habits vary.
• In grazers, such as chitons and some snails, the radula is used to scrape or rasp algae from hard surfaces. They have relatively simple digestive systems that efficiently process hard-to-digest algal material. -Carnivorous snails have modified radula that capture prey or act as drills to cut through the shells of other organisms.
• Filter feeders, such as bivalves, don’t have a radula. Instead they trap food particles using long strings of mucous that are then filtered and sorted out by cilia on the gills.
• Cephalopods are carnivores with efficient and rapid digestive systems.

Question 57

Generally describe the nervous system and behavior of molluscs.

Answer 57

• The nervous systems of molluscs display a wide range of complexity.
• Gastropods, bivalves, and chitons have relatively simple behaviors and therefore simple nervous systems.
• Cephalopods, however, have the most complex nervous systems of all invertebrates
• The brain is divided into regions, each of which controls different functions and behaviors.
• The amazingly complex eyes of the cephalopods are crucial to their hunting abilities and testify to the highly developed nervous systems of the cephalopods.

Question 58

Generally describe reproduction and life history of molluscs.

Answer 58

• Most molluscs have separate sexes but some are hermaphrodites
• In bivalves, chitons, and some gastropods, reproduction is by spawning and fertilization occurs externally in the water.
• Most gastropods and all cephalopods have internal fertilization.

Question 59

Describe the Kingdom Animalia.

Answer 59

• Members are multicellular and cannot manufacture their own food—They are heterotrophs.
• The need to obtain food (energy) from others has resulted in a diverse array of feeding styles in animals (carnivores, herbivores, scavengers, omnivores, etc.)