Download Zoology * Chapter 9 * Multicellular and Tissue Levels of Organization

Zoology – Chapter 9 – Multicellular and Tissue Levels of Organization
Multicellular life has been a part of the earth’s history for about __________ million years, but represents only ________ of
the earth’s geological history. The evolutionary events that lead to multicellularity is a ______________. Many zoologists
believe that multicellularity could have arisen as ________________ cells remained ______________, in the form of colonial
protists, which is known as the ________________ _______________. A second method called the ______________
_______________ was proposed. A syncytium is a _____________, multinucleate cell. The formation of ____________
________________ in the cytoplasm of a syncytial protist could have produced a ____________, multicellular organism.
Animal Origins
The animal kingdom is most likely monophyletic, where organisms descended from a _____________ ancestor.
Phylum Porifera – Cell Types, Body Wall, and Skeletons
The Porifera, or _____________ are primarily _____________ animals consisting of loosely organized ________ with about
_______ thousand species of different __________. Characteristics of the phylum Porifera include: 1. _________________
2. ___________ cell types: pinacocytes, mesenchyme cells, and choanocytes 3. _____________ cavity , or a series of
branching ______________ through which ____________ circulates during ____________ feeding 4. _______ tissues or
organs. 5. _____________ (stationary). Pinacocytes are _________ flat cells that __________ the outer surface of a sponge.
Below the pinacocyte is a ____________ jellylike layer called the mesohyl. Amoeboid cells called mesenchyme cells move
about in the mesohyl and are specialized for ______________, secreting skeletal elements, transporting and storing ________,
and forming contractile ___________ around the openings in the sponge ________. Choanocytes are cells with a
_________________ surrounded by a collar of _______________ that ________ food particles. Sponges are supported by a
_____________ that may consist of _______________ needlelike spikes called _____________. Spicules are formed by
_______________ cells and made of calcium carbonate or silica. The skeleton is also made of _____________.
Water Currents and Body Forms
The life of a sponge depends on the ____________ ___________ that choanocytes create. Water currents bring _________ and
___________ to a sponge and carry away metabolic and digestive ______________. The simplest and ___________ common
sponge ________ ___________ is the ascon which is vaselike. _______________ are the outer _________________ of
porocytes and lead to the spongocoel which is lined with ________________________. Choanocytes have _______________
that help bring in food particles through the ostia by the _____________ ____________. _______________ sponges have a
_______________ canal system where water enters the sponge through ostia and moves through the branched _____________
Canals and out ___________________ canals.
Maintenance Functions
Sponges feed on microscopic algae, _______________, and protists, and suspended organic matter. Choanocytes
____________ the small food particles. Suspended food is trapped on the ______________ and moved along _____________
to the base of the collar, where it is incorporated into a __________ ___________. Sponges may also ______________ by
____________ transport nutrients dissolved in seawater. Sponges do not have _______________ cells to coordinate body
__________________. Amoeboid cells transmitting _________________ messages and _________ movement over cell
surfaces are ______________ mechanisms.
Reproduction
Most sponges are monoecious (_________ _________ occur in the same individual) but __________ _________ self-fertilize
because individual sponges produce ___________ and ______________ at different times. Some choanocytes lose their
____________ and _____________ and undergo meiosis to form flagellated ___________. Other choanocytes undergo
meiosis to form ___________. Sperm and eggs are released from sponge _____________, and fertilization occurs in the
___________ water, and planktonic larvae develop. The larva break free, and __________ currents carry the larva out of the
_____________ sponge. After ________ days of a free-swimming existence, the larva ____________ to the substrate and
begins to develop into the __________ _________form. ________________ reproduction of freshwater and some marine
sponges involves the formation of resistant ________________ called ______________. When the parent sponge ______ in
the winter, it releases gemmules which can ______________ both freezing and drying. Some sponges can ________________.
Phylum Cnidaria
Members of the phylum Cnidaria possess _____________ or ______________ symmetry. The Cnidaria include over _______
Thousand species, are mostly _____________, and are important in ________ _________ ecosystems. Characteristics of the
phylum Cnidaria include: 1. _____________ symmetry or modified as _________________ symmetry 2. Diploblastic,
____________-level organization 3. Gelatinous mesoglea between the ________________ and gastrodermal tissue layers
4. Gastrovascular ____________ 5. ____________ system in the form of a ________ __________ 6. Specialized cells,
cnidocytes, used in ______________, ______________, and attachment.
The Body Wall and Nematocysts
Cnidarians possess ___________________, tissue-level organization. Cells organize into _____________ that carry out
specific functions, and all cells are derived from ______________ embryological layers. The ectoderm of the embryo gives
rise to an outer layer of the body wall, called the ___________________, and an inner layer of the body wall, called the
__________________, is derived from endoderm. Between the epidermis and gastrodermis is a jellylike layer called
________________. One kind of cell is characteristic of this phylum is epidermal and/or gastrodermal cells called
_______________, that produce structures called cnida, which are used for attachment, ______________, and feeding.
___________________ are a type of cnida used in food gathering and defense that may discharge a long tube armed with
______________ spikes that penetrates the prey and paralyzes them.
Alternation of Generations
Most cnidarians possess __________ body forms in their life histories. The ___________ is usually ___________ and
___________. It attaches to a substrate at the _____________ end, and has a cylindrical body, called the ______________, and
a mouth surrounded by food-gathering tentacles. The ____________ is dioecious and free swimming. It is shaped like an
inverted bowl, and _____________ dangle from its margins. When a cnidarian life cycle involves both ____________ and
_______________ stages, the phrase “___________________ of ______________________” is applied.
Maintenance Functions
The gastrodermis of all cnidarians lines the _____________________ cavity. This cavity functions in ____________, the
exchange of respiratory gases and __________________ wastes, and the discharge of _______________. The Food of most
cnidarians consist of very small ___________________ and some small fish. Cnidarians get most of their support from the
buoyancy of __________ around them. They also have a _________________ _____________ that aides in support and
movement. A hydrostatic skeleton is water or _____________ _______________ confined in in a cavity of the body and
against which ________________ elements of the body wall act. Polyps use a variety of forms of _________________. They
move by somersaulting from base to ________________ and from tentacles to base again, or they move in an
______________ gliding fashion. Medusa move by swimming and ______________ with the water currents. Cnidarians have
a nerve net , which consist of nerve cells located ______________ the epidermis near the mesoglea, and interconnect to form a
two-dimensional structure.
Reproduction
Most cnidarians are ________________, and ______________ and _____________ may be released into the gastrovascular
cavity or to the outside of the body. A blastula forms early in development, and migration of surface cells to the interior fills
the ________________ with cells that will form the gastrodermis. The embryo elongates to form a ciliated, __________swimming larva called a _______________. The planula attaches to a substrate, interior cells __________ to form the
gastrovascular cavity and a young _____________ develops.
Class Hydrozoa
Hydrozoans are _____________ and ________________ organisms. Most hydrozoans have life cycles that display
________________________ of _________________. Three features distinguish hydrozoans from other cnidarians: (1)
nematocysts are only in the ___________________; (2) ________________ are epidermal and released to the
_______________ of the body rather than into the gastrovascular cavity; and (3) the mesoglea is _______________. Most
hydrozoans have _____________ polyps in which individuals may be specialized for ______________, producing medusa by
_______________, or defending the colony. In Obelia, a marine cnidarian , the planual develops a _____________ polyp
called a ___________________. Obelia also grow a __________________ polyp that produces medusae by budding and is
called a _________________. The mouth is at the end of a tubelike _________________ that hangs from the medusa’s oral
surface. The ___________ __________ coordinates swimming movements, and embedded in the mesoglea around the margin
of the medusa are sensory structures called ________________. ____________ is a common freshwater hydrozoan that hangs
from the underside of floating ___________ in clean streams and ponds. Hydra lacks a medusa stage and reproduces both
______________ by _______________ from the side of the polyp and _________________. The sexual reproduction occurs
in the _______________ stage.
Class Scyphozoa
Members of the class Scyphozoa are all _______________ and are “__________ _____________” because the dominate
Stage in their life history is the _____________. Unlike hydrozoan medusae, scyphozoan medusae lack a ____________, the
mesoglea contains amoeboid mesenchyme cells, ________________ occur in the gastrodermis as well as the epidermis, and
________________ are gastrodermal in origin. Many scyphozoans are ___________________ and some have a dangerous
_____________ they possess. Aurelia is a common scyphozoan in both _____________ and _______________ oceans.
Aurelia is a _______________ feeder, and has _____________ specialized structures called _______________ that consists of
sensory structures. Scyphozoans are ___________________. Aurelia’s __________ gonads are in gastric pouches, _________
per pouch. _____________ are released into the gastric pouches. ____________ swim through the mouth to the outside of the
medusa. In some scyphozoans, _________ are fertilized in the female’s ______________ ____________, and early
development occurs there. In Aurelia, ____________ lodge in the oral lobes, where fertilization and development to the
_______________ stage occur. The planula develops into a ______________ called a scyphistoma, which lives a year or more
during which time budding produces miniature medusae, called _________________. Ephyrae pile up on top of one another
and after they are released they gradually attain the _______________ form.
Club Cubozoa
The medusa is ______________ and ______________ hang from each of its corners. Polyps are _____________, and
cubozoans are active _______________ and _______________ in _________ tropical waters.
Class Anthozoa
Members of the class Anthozoa are ______________ or solitary, lack medusae, and are all ____________. They include
anemones and stony and soft ___________. Anthozoan polyps differ from hydrozoan polyps in ___________ ways: 1. the
mouth of an anthozoan leads to a _________________, an invagination of the body wall that leads into the gastrovascular
cavity; 2. mesenteries (membranes) that bear cnidocytes and _____________ on their free edges divide the gastrovascular
cavity into sections; and 3. the _____________ contains amoeboid mesenchyme cells. Sea anemones are solitary, sometimes
_______________, and _____________ organisms that attach to its substrate, some _____________ in soft substrates , and
some live in symbiotic relationships. The polyp attaches to its substrate by a __________ _________ . An __________ disk
contains the __________ and hollow, oral tentacles. Anemones have limited __________________. They glide on their pedal
disks, crawl on their sides, and walk on their __________________. Anemones feed on invertebrates and __________.
Anemones have both __________________ and __________________ reproduction. In asexual reproduction, a piece of
___________ disk may break away from the polyp and __________ into a new individual in a process called pedal laceration.
Longitudinal or transverse ____________ may divide one individual into two, with missing parts being __________________.
Anemones may be either monoecious or dioecious. In monoecoius species, __________ gametes mature earlier than
_________ gametes so that self-fertilization does not take place, called protandry. _____________ occur in longitudinal bands
behind mesenterial filaments. Fertilization may be ___________ or within the gastrovascular cavity. _______________ results
in the formation of a planula, which develops into a ciliated larva that settles to the substrate, ______________, and eventually
forms the adult. Other anthozoans are ___________. Stony corals form ______________ ____________ and have
exoskeletons made of calcium carbonate. When threatened polyps retract into their protective ______________________.
Many cnidarians have developed close _____________________ relationships with unicellular ________________.
Phylum Ctenophora
Animals in the phylum Ctenophora are called _____________ _____________ or _____________ ______________. There
__________ species and all are _____________. Characteristics of the phylum Ctenophora include: 1. Dipoblastic or possibly
tripoblastic, ___________-____________ organization 2. __________________ symmetry 3. Gelatinous, cellular __________
between the epidermal and gastrodermal tissue layers 4. _________ ____________ cells develop within the mesoglea. 5.
__________________ cavity 6. Nervous system in the form of a __________________ __________________ 7. Adhesive
structures called ____________________ 8. _____________ rows of ciliary bands called comb rows for _________________.
Tentacles possess contractile fibers that ________________ the tentacles, and __________________ cells called colloblasts,
that ___________________ prey. ___________________ occurs as the tentacles wipe the prey across the mouth. Ctenophores
have an ____________ opening to eliminate waste. Ctenophores are all _______________________.