Lab 10 Flashcards
(86 cards)
1
Q
Kingdom Animalia (Part 2)
A
- *3. Phylum Platyhelminthes** – flatworms
- *4. Phylum Annelida** – earthworms, marine worms, leeches
- *5. Phylum Mollusca **
a) Class Bivalvia – scallops, clams, oysters
b) Class Gastropoda – snails, slugs
c) Class Cephalopoda – octopuses, squid, cuttlefish, chambered nautilus
2
Q
Class Bivalva
A
scallops, clams, oysters
3
Q
Class Gastropoda
A
snails, slugs
4
Q
Class Cephalopoda
A
octopuses, squid, cuttlefish, chambered nautilus
5
Q
Commonalities between Phylum Platyhelminthes, Phylum Annelida, and Phylum Mollusca
A
- They are triploblastic.
- They are bilaterally symmetrical. (Thus, these animals are all called bilaterians!)
6
Q
triploblastic
A
Triploblasty is a condition of the blastula in which there are three primary germ layers: the ectoderm, mesoderm, and endoderm. The germ layers form during gastrulation of the blastula. Additionally, the term may refer to any ovum in which the blastoderm splits into three layers.[1]
7
Q
bilateral symmetry
A
Many animals have a body form that is symmetrical, meaning that it could be divided into matching halves by drawing a line down the center. In this respect, arthropods are built like humans are; the right half of an arthropod is a mirror image of its left half — this is called bilateral symmetry
8
Q
cephalization
A
the evolutionary concentration of feeding and sensory
structures at one end of the body
9
Q
bilateral symmetry and cephalization are closely associated
A
Thus, animals with bilateral symmetry generally have a very distinct head.
10
Q
How is cephalization adaptive for motile animals?
A
there is an advantage in having the end that goes first, as the animal moves, fitted out with sense organs—on the premise that it is better to know where you are going than where you have been. Because a lot of computational power is needed to deal with sensory stimuli, the nervous system tends to be larger in the head as well. And finally, food can be captured more effectively if the mouth is also at the front of the body
11
Q
Earthworm Body Plan (Tube-within-a-Tube)
A
12
Q
Many bilateran animals have what kind of body organization?
A
Tube-within-a-tube (e.g. earthworm)
13
Q
Inner tube/Outer tube
A
Inner Tube = gut/digestive system
Outer Tube = body wall
14
Q
coelom
A
the fluid-filled space between the digestive tube and the outer body wall
15
Q
function of ceolom
A
In addition to providing space for internal organs and
fluid for circulation of oxygen and nutrients, the coelom acts as a hydrostatic skeleton in some animals. The fluid-filled body cavity is pressurized (like a turgid water balloon). Muscle contraction against the pressurized coelom changes the body’s shape and generates movement.
16
Q
Phylum platyhelminthes
A
flatworms
17
Q
do flatworms have a coelom?
A
No, they are aceolomate (meaning they lack a ceolom). Solid tissue occupies the region between the gut and the body wall.
18
Q
Acoelomates
A
19
Q
Planaria
A
A free-living (i.e. not parasitic) flatworm
They live in streams, ponds, and moist terrestrial environments.
20
Q
Planaria Movement
A
These soft bodied, ciliated flat worms move much like slugs in an undulating motion.
Planarians move by beating cilia on the ventral dermis, allowing them to glide along on a film of mucus. Some also may move by undulations of the whole body by the contractions of muscles built into the body membrane.[3]
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Q
Planaria - Structures
A
Identify the following structures and describe their function: head, eyespots, auricles (chemosensory
structures), gastrovascular cavity, pharynx (tube connecting the mouth to the gastrovascular cavity).
22
Q
Function of a Planaria’s Head
A
(cephalization) where accumulation of nervous tissue and sensory structures occurs.
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Q
Function of a Planaria’s Eyespots
A
The eye spots are sensitive to light
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Q
Function of Planarian’s Auricles
A
There are two auricles (earlike projections) at the base of the head, which are sensitive to touch and the presence of certain chemicals.
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Function of Planarian's Gastrovacular Cavity
gastrovascular cavity. This structure branches throughout the body allowing nutrients from food to reach all extremities; this is where digestion occurs
## Footnote
The food enters the gastrovascular cavity through the pharynx located at the center of the planarian's underside and is digested into feces and monomers.
The feces exit through the pharynx and the monomers are absorbed by the tissues from the gastrovascular cavity. The gastrovascular cavity is multiply-branched and so virtually all cells are near one of the branches. Not a true circulatory system - no blood or blood vessels.
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Function of the Planarian's Pharynx
The pharynx connects the mouth to the gastrovascular cavity.
a muscular tube through which the flatworm can suck food into its gastrovascular cavity. The opening into the pharynx could be considered the mouth, but since this animal has a two-way gut, that opening also must function as the anus.
Mouth on the ventral surface allows muscular pharynx to be extended and inserted into prey
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Planarian's pharynx part II
Mouth on the ventral
surface allows
muscular pharynx to
be extended and
inserted into prey
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How is undigested food eliminated by the planaria?
Undigested food is eliminated out the
mouth and through the pharynx (just like in
phylum cnidaria)
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Tapeworm specimen
long, whitish, worm
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Taenia slides
Taenia is a tapeworm that lives in the gut of its host. At the anterior of its body, a scolex, which has barbs
and suckers, attaches the worm to the host’s intestinal lining. The long flat body absorbs nutrients, and
produces reproductive segments called proglottids. Mature proglottids are filled with fertilized eggs, and
they break off from the posterior end of the worm and are eliminated along with the host’s waste to
continue the life cycle.
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Scolex of Taenia
The worm's scolex ("head") attaches to the intestine of the definitive host. In some species, the scolex is dominated by bothria, or "sucking grooves" that function like suction cups. Other species have hooks and suckers that aid in attachment.
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Proglottids of Taenia
The body is composed of successive segments (proglottids). The sum of the proglottids is called a strobila, which is thin, and resembles a strip of tape. From this is derived the common name "tapeworm". Like some other flatworms, cestodes use flame cells (protonephridia), located in the proglottids, for excretion. Mature proglottids are released from the tapeworm's posterior end and leave the host in feces.
Because each proglottid contains the male and female reproductive structures, they can reproduce independently.
Once anchored to the host's intestinal wall, the tapeworm absorbs nutrients through its skin as the food being digested by the host flows past it and it begins to grow a long tail, with each segment containing an independent digestive system and reproductive tract. Older segments are pushed toward the tip of the tail as new segments are produced by the neckpiece. By the time a segment has reached the end of the tail, only the reproductive tract is left. It then drops off, carrying the tapeworm eggs to the next host, since, by that point, the proglottid is, in essence, a sac of eggs.
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What type of digestive system do tapeworms have?
Incomplete.
Tapeworms have no digestive systems as adults, which makes sense for an animal that already absorbs several materials through its surface and lives inside an intestine.
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Phylum Annelida
segmented worms
| (earthworms, marine worms, and leeches)
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Common characteristics of segmented worms
All of these worms exhibit body segmentation, which means that their body is organized as a series of similar, repeated units. They also have a coelom, which functions as a hydrostatic skeleton.
In annelids, the first body segment, called the prostomium, is positioned above the mouth and may bear various sensory structures in some worms. Annelid worms also possess bristle-like structures, called chaetae, which extend from the body segments and function in movement
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What type of feeder is an earthworm
a deposit feeder
Earthworms are deposit feeders, which means they burrow through sediment and digest the organic
material within it. Many morphological characteristics of earthworms are directly associated with this
feeding strategy
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clitellum
The smooth, saddle-like structure near the middle of the earthworm’s body is called the clitellum, and it
functions in earthworm reproduction.
The Clitellum is actually used to secrete a sticky fluid which forms a sac for its eggs.
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Identify the following structures and know their
function: **prostomium**
Prostomium - Some species of earthworms have a tongue-like lobe above the mouth called prostomium. The prostomium is actually a sensory device. Earthworms do not have a nose, eyes, ears, or hands to gather sensory information about their environment. Instead, they depend on their prostomium and sensory receptors in their skin to "feel" their way through the soil.
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Identify and know the following structures and their functions: Clitellum of the earthworm
Clitellum - Adult (sexually mature) earthworms have a distinct swelling called a clitellum. It is located about one-third of the way down the earthworm. The clitellum is often white or orange in colour. It produces most of the material secreted to form earthworm cocoons. The clitellum forms a band that can be flared, non-flared, saddle-shaped, or annular. It is generally found between segments 26 and 33.
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Identify and know the following structures and their function: Chaetae on the earthworm
Chaetae - bristles that are involved in the locomotion of the worm
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Does the earthworm exhibit segmentation?
Yes, they have a repitition of body segments known as segmentation.
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Do earthworms show cephalization?
Yes, there is a typical head, with a mouth and sensory organs and processors (exhibition of cephalization).
It exhibits some limited cephalization.
Earthworms use their pharynxes to suck soil and detritus into their esophagus. This has a limited impact on its feeding strategy.
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Earthworm: circular muscles and longitudinal muscles
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Earthworm's internal anatomy (cross-section)
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Tube-within-a-tube anatomy (earthworm)
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Typhosole (earthworm)
In earthworms, it is a dorsal flap of the intestine that runs along most of its length, effectively forming a tube within a tube, and increasing the absorption area by that of its inner surface. Its function is to increase intestine surface area for more efficient absorption of digested nutrients.
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Marine worms (polychaetes)
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Do marine worms exhibit segmentation?
Yes.
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Chaetae (marine worms vs. earthworms)
Marine worms have more chaetae per segment than earthworms.
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Amount of cephalization in marine worms
Greater cephalization than other
annelids, but mainly in mobile forms
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Feeding strategy of polychaetes (marine worms)
Some are predators with an extensible proboscis
Some possess poison glands
Others are herbivores, scavengers, or detritivores
Fan worms filter feed
\*more cephalization required to be a predator
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Leeches
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Leeches - description and feeding
Leeches are parasitic annelid worms.
They obtain their food by:
Most leech species do not feed on human blood, but instead prey on small invertebrates, which they eat whole. To feed on their hosts, leeches use their anterior suckers to connect to hosts for feeding. Once attached, leeches use a combination of mucus and suction to stay attached and secrete an anticoagulant enzyme, hirudin, into the hosts' blood streams
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Do leeches exhibit segmentation?
Yes, but the external segmentation does not correspond to the internal segmentation of their organs.
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Suckers on Leeches
Function: leeches all have an anterior (oral) sucker formed from the first six segments of their body, which is used to connect to a host for feeding. It also releases an anaesthetic to prevent the host from feeling pain while it sucks blood. They use a combination of mucus and suction (caused by concentric muscles in those six segments) to stay attached and secrete an anti-clotting enzyme, hirudin, into the host's blood stream. The medicinal leech (Hirudo medicinalis) has two suckers, one at each end, called the anterior and posterior sucker. The posterior is mainly used for leverage while the anterior sucker, consisting of the jaw and teeth, is where the feeding takes place.
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Phylum Mollusca
mollusks
Mollusks are a diverse group of animals found primarily in marine and freshwater aquatic environments. The
group includes animals such as clams, oysters, octopuses, squids, snails, and slugs
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Features of Mollusks
Like annelids, mollusks have a
coelom and a complete digestive system. Mollusks are also soft-bodied; however, most possess a protective
exoskeleton, a shell, made of calcium carbonate.
```
The general mollusk body plan consists of three
basic parts (as illustrated in this snail diagram)…
```
* visceral mass – sack containing internal organs
* foot – muscular structure for locomotion
* mantle – thin tissue layer that secretes the shell
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Classes within the Phylum Molluska
**Class Gastropoda** includes snails and slugs.
**Class Bivalvia** includes mollusks such as clams, oysters, and mussels
**Class Cephalopoda** includes the most predatory mollusks, such as squids and octopuses.
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Radula
Gastropods have a feeding-structure called a radula, which is located inside the mouth and covered with small, chitinous teeth. Most gastropods use the radula to scrape algae or other microorganisms off of a substrate; however, some predatory snails have a specialized radula for unique feeding strategies. For example, moon snails (discussed in our first lab) have a radula that secretes acid and drills through clam shells.
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Gastropa (snails, slugs) Foot
Identify the foot and exoskeleton
Function: The Foot - a large part of a snail's body can be seen extended outside of the shell, when the snail is crawling around. This body part is flattened at the belly side (ventrally) to form a flat crawling sole and mainly is used for locomotion.
Exoskeleton: The gastropod shell is an external skeleton or exoskeleton, which serves not only for muscle attachment, but also for protection from predators and from mechanical damage. In land snails, in some freshwater snails and in intertidalmarine snails, the shell is also an essential protection against the sun, and against drying out.
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Do Gastropods exhibit cephalization?
feature of gastropods is the greater degree of cephalization in which the head is usually well developed with one or more than one pairs of tentacles
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Radula
Gastropods have a feeding-structure called a radula, which is located inside the mouth and covered with small, chitinous teeth.
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How many shells do most gastropods have?
Most have one shell
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Gastropods (shell)
Not all gastropods have a shell (ex. banana slug)
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What is the difference between a snail and a slug?
Snails have a shell.
Snail-like animals that naturally lack a shell, or have only an internal shell, are usually called slugs,
Other than that there is little morphological difference between slugs and snails.
There are however important differences in habitats and behaviour. A shell-less animal is much more maneuverable and compressible, so even quite large land slugs can take advantage of habitats or retreats with very little space, retreats that would be inaccessible to a similar-sized snail.
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Common Features of: Class Bivalvia (includes mollusks such as clams, oysters, and mussels)
Most of the animals in this group are
filter-feeders. The incurrent and excurrent siphons generate a current of water that flows over the gills, and the gills trap small food particles from the water. They are called bivalves because they possess two valves (i.e. shells) connected at the hinge.
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Bivalve shells
They have 2 shells connected with a hinge.
The mantle, a thin membrane surrounding the body, secretes the shell valves
The mantle lobes secrete the valves
Function: to support the soft inner bodies and protection from predators
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Adductor muscles of Bivalves
The adductor muscles are the main muscular system in bivalve
Adductor muscles leave noticeable scars or marks on the interior of the shell's valves. (the white part)
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Adductor muscle scars (bivalves)
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Function of adductor muscles in bivalves
These strong muscles connect the two valves and contract in order to close the shell. They work in opposition to the ligament which tends to pull the valves apart.[16]
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Do bivalves exhibit cephalization?
Mollusks show a great diversity of nervous systems. Some mollusks such as bivalves have no cephalization.
Bivalves are filter-feeders, meaning they do not require a concentration of neurons in a head area to enable feeding as a predator.
Slow-moving animals have some cephalization, enabling sensory reception as the animal moves through the environment. The active predatory lifestyle of cephalopods require complex sense organs; they are highly cephalized.
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External Anatomy of a Clam
Identify the following structures
associated with external anatomy:
hinge, umbo, left valve, right valve
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Internal Anatomy of a Clam
Identify the following structures associated with internal anatomy and know their function:
- anterior adductor muscle
- posterior adductor muscle
- mantle
- foot
- visceral mass,
- incurrent & excurrent siphons
- gills (ctenidia)
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Function of Adductor Muscles in Clams
Opening and closing the shell of the clam is the function of the adductor muscle in clam
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Function of the mantle in a clam
it is the dorsal body wall which covers the visceral mass and usually protrudes in the form of flaps well beyond the visceral mass itself.
In many, but by no means all, species of molluscs, the epidermis of the mantle secretes calcium carbonate andconchiolin, and creates a shell.
(in some it protects it from bright sunlight)
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Function of the foot of a clam
works as one of the two nerves in the clam system and ancors the body/ helps with movement
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Function of the Visceral Mass of the Clam
The visceral mass is located on top of the head-foot and contains internal organs that perform the functions of digestion, circulation, reproduction and excretion.
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Function of Incurrent and Excurrent Siphons
The more ventral opening is the incurrent siphon that carries water into the clam and the more dorsal opening is the excurrent siphon where wastes & water leave.
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Function of the gills in clams
Respiratory structures
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Class Cephalopoda
includes the most predatory mollusks, such as squids and octopuses. One extant member of this group, the chambered nautilus, has an elaborate shell with chambers used for buoyancy. Chambers are added to the shell as the animal grows. All other extant members of this group have either a thin, internal shell (e.g. squid) or have lost the shell entirely (e.g. octopus).
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Cephalopods and shells
All cephalopods do not have shells (ex. squids)
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Cephalopods and cephalization
Cephalopods exhibit a high degree of cephalization
To feed: All living cephalopods have a two-part beak;[6]:7 most have a radula, although it is reduced in most octopus and absent altogether in Spirula.[6]:7[57]:110 They feed by capturing prey with their tentacles, drawing it into their mouth and taking bites from it.[14] They have a mixture of toxic digestive juices, some of which are manufactured by symbiotic algae, which they eject from their salivary glands onto their captured prey held in their mouth. These juices separate the flesh of their prey from the bone or shell.[14] The salivary gland has a small tooth at its end which can be poked into an organism to digest it from within.[14]
This type of feeding requires a large concentration of neurologic actiivity in the head to be able to act as a predator and capture prey.
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Arms and Tentacles of Cephalopods
Arms are shorter,
Tentacles are longer
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Functions of the Arms and Tentacles of Cephalopods
The tentacles perform the function of grabbing prey and holding on to it. There are hooks on the arms as well as the tentacles of squids but the ones on the tentacles can swivel while those on the arm cannot. These help squids hold on to their prey better while the prey tries to escpe.
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Animal Lineage: Protosomes
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