Page 168 - Ultimate Visual Dictionary (DK)

ANIMALS

Sponges, jellyfish, INTERNAL ANATOMY OF A SPONGE

Amoebocyte Osculum
and sea anemones (excurrent pore)

Choanocyte
(collar cell)
SPONGES ARE MAINLY MARINE animals that make
Ostium
up the phylum Porifera. They are among (incurrent pore)
the simplest of all animals, having no
Porocyte (pore cell)
tissues or organs. Their bodies consist
of two layers of cells separated by a Mesohyal
jellylike layer (mesohyal) that is strengthened
Spongocoel
by mineral spicules or protein fibers. The body
(atrium; paragaster)
is perforated by a system of pores and water
channels called the aquiferous system. Special Spicule
cells (choanocytes) with whiplike structures Pinacocyte
(flagella) draw water through the aquiferous (epidermal cell)
system, thereby bringing tiny food particles
Ostium (incurrent pore)
to the sponge’s cells. Jellyfish (class Scyphozoa),
sea anemones (class Anthozoa), and corals
(also class Anthozoa) belong to the EXTERNAL FEATURES
SKELETON OF A SPONGE OF A SEA ANEMONE
phylum Cnidaria, also known as
Coelenterata. More complex than
Protein matrix
sponges, coelenterates have simple
tissues, such as nervous tissue;
a radially symmetrical body;
and a mouth surrounded by
tentacles with unique stinging
cells (cnidocytes).

EXAMPLES OF SEA ANEMONES Pore
Tentacle
PARASITIC ANEMONE
(Calliactis parasitica)
JEWEL ANEMONE
(Corynactis viridis)
PLUMOSE ANEMONE MEDITERRANEAN SEA ANEMONE
(Metridium senile) (Condylactis sp.)

GREEN SNAKELOCK
ANEMONE
(Anemonia viridis)

BEADLET ANEMONE
(Actinia equina)
GHOST ANEMONE
(Actinothoe
sphyrodeta)

Sagartia elegans

166