ACT 10 - CLASSIFYING ANIMALS

Question 1

consists of animals called SPONGES,
which are the SIMPLEST MULTICELLULAR ANIMALS.

Sponges have bodies organized on the cellular
level and DO NOT FORM TRUE TISSUES OR ORGANS.

Their bodies are divided into CAVITIES by certain
cells, allowing each cell to carry out life
activities.

Body is perforated with PORES and CANALS for
the entrance and exit of water, food, and
waste.

Sponges LACK A DIGESTIVE TRACT and well defined tissues.

Answer 1

Phylum PORIFERA

Question 2

PORIFERA

UNIQUE CHARACTERISTICS

Answer 2

•Skeleton composed of SPICULES or FIBERS
(CALCIUM CARBONATE, SILICA, SPONGIN, ARAGONITE).

•Types and arrangements of spicules vary by
class (e.g., CALCAREOUS, SILICEOUS, SPONGIN, HARD
ARAGONITE).

•Most species are generally STERILE WITH NO
EVIDENT REPRODUCTIVE ORGANS.

•Each CELL FUNCTIONS INDEPENDENTLY, unlike more
complex animals.

Question 3

CLASSES under Phylum Porifera

Answer 3

CALCAREA
HEXACTINELLIDA
DEMOSPONGIAE
HOMOSCLEROMORPHA

Question 4

members are typically SMALL, MARINE
SPONGES WITH SIMPLE SHAPES, and they play an
important role in FILTERING SEAWATER.

Unique characteristics

-Sponges with spicules made of CALCIUM
CARBONATE, which may have ONE, THREE, OR FOUR
RAYS.

-Bodies are generally TUBULAR or VASE-SHAPED
and found in SHALLOW MARINE HABITATS.

Representative - SYCON
Sycon is a tubular CALCAREOUS SPONGE that is
commonly used for laboratory studies due to
its CLEAR ANATOMY and ease of observation.

Answer 4

CLASS CALCAREA

Question 5

are mostly found in DEEP MARINE
ENVIRONMENTS and are known for their DELICATE
AND ELABORATE SKELETAL forms.

Unique characteristics
-Sponges with SKELETONS composed of
SILICEOUS, SIX-RAYED (HEXACTINE) SPICULES fused
into intricate, GLASS-LIKE LATTICES.

-Their cells are often connected in a SYNCYTIAL
STRUCTURE, forming a CONTINUOUS NETWORK.

Representative - EUPLECTELLA
Euplectella, or the VENUS’ FLOWER BASKET, is a
deep-sea glass sponge famous for its elegant
LATTICE SKELETON and for hosting SYMBIOTIC
SHRIMP inside its body.

Answer 5

CLASS HEXACTINELLIDA

Question 6

make up the MAJORITY OF
SPONGE SPECIES, occupying both FRESHWATER
AND MARINE ENVIRONMENTS with a wide range of
ecological roles.

Unique characteristics
-Sponges with skeletons that consist of
SPONGIN FIBERS, SILICEOUS SPICULES, OR A
COMBINATION OF BOTH, but never calcium
carbonate.
-They exhibit the GREATEST DIVERSITY IN FORM, SIZE,
AND HABITAT among all sponge classes.

Representative - SPONGILLA
Spongilla is a freshwater sponge that grows as
GREENISH MASSES ON SUBMERGED SURFACES,
benefiting from symbiotic algae that give it
color.

Answer 6

CLASS DEMOSPONGIAE

Question 7

are usually found in
SHALLOW MARINE environments, often forming
THIN, COLORED CRUSTS on rocks and other
surfaces.

Unique characteristics
-Sponges with simple, ENCRUSTING FORMS and
SILICEOUS SPICULES that are EITHER VERY SIMPLE OR
ABSENT.
-Has a BASAL MEMBRANE under the epithelium,
which is unique among sponges.

Representative - OSCARELLA
Oscarella is a GENUS OF SMALL, SOFT-BODIED
SPONGES with no spicules, commonly observed
growing on shaded marine rocks.

Answer 7

CLASS HOMOSCLEROMORPHA

Question 8

are SEGMENTED,
BILATERALLY SYMMETRICAL,
TRIPLOBLASTIC COELOMATE
animals with a SOFT, ELONGATED
BODY divided into RING-LIKE
segments. They possess a
COMPLETE DIGESTIVE TRACT, a
CLOSED CIRCULATORY SYSTEM,
paired NEPHRIDIA, and a
VENTRAL NERVE CORD, and they
occur in marine, freshwater,
and terrestrial habitats.

Answer 8

ANNELIDA

Question 9

ANNELIDA

UNIQUE CHARACTERISTICS

Answer 9

Body Segmentation: TRUE METAMERISM, with each segment containing REPEATED ORGANS AND COELOMIC COMPARTMENTS.

Digestive System: COMPLETE, STRAIGHT, AND
REGIONALLY SPECIALIZED GUT.

Circulatory System: CLOSED CIRCULATORY SYSTEM
WITH BLOOD CONTAINING respiratory pigments.

Excretory System: PAIRED NEPHRIDIA present in most segments for excretion.

Nervous System: DORSAL CEREBRAL GANGLIA (brain) and paired VENTRAL NERVE CORD; SEGMENTAL NERVES PRESENT.

Locomotion: Muscular body wall (circular and longitudinal muscles) and often setae or parapodia aid in movement.

Reproduction: Sexual, dioecious or monoecious; development may involve trochophore larva in marine forms.