• Common throughout marine, freshwater,
terrestrial, and even aerial environments
• Body usually segmented and jointed externally
(divided into 3 major parts: head, thorax,
abdomen) with appendages that are equipped
for feeding, sensory reception, defense, and
locomotion; with hardened exoskeleton
containing chitin and molted at intervals
Complete digestive tract
(mandible-chewing or proboscissucking) with a dorsal heart and a
ventral nervous system
Sensory organs include antennae
and hairs, simple and compound
Reproduces (mostly sexually), one
to several larval stage
The muscle system is
more or less assisted
originated from the
created by the heart
gills, trachea, book
lungs or body surface
With open circulatory
REPRESENTATIVE ORGANISMS: Ants, Butterfly,
Grasshopper, Beetles, Lobsters, Spiders etc.
• CLASS TRILOBITA – Trilobites
• CLASS ARACHNIDA – Spiders, Scorpions, Ticks
• CLASS MEROSTOMATA – Horseshoe crabs
• CLASS PYCNOGONIDA – Sea spiders
• CLASS CEPHALOCARIDA – Horseshoe
• CLASS MAXILLOPODA – Barnacles, and
• CLASS MALACOSTRATA – Lobsters,
• CLASS CHILOPODA – Centipedes
• CLASS DIPLOPODA - Millipedes
• CLASS INSECTA – Insects
• Class Branchiopoda – Brine shrimp
Insects that have piercing and sucking
mouthparts are called BUGS while BEETLES are
insects distinguished as those having forewings
modified into hard wing cases that cover and protect
the hind wings and abdomen!
• Echinoderms are chiefly marine
invertebrates. They have bodies
covered with spines. Their bodies
are composed of calcuim
• They have a water vascular system ,
which function for locomotion,
respiration, and feeding. The tips of
the tube feet contain most of the
organism’s sensory neurons. The
tube feet are used to attach to
objects, for protection, as well as to
● Sexual reproduction in echinoderms
usually involves the release of gametes
by separate males and females into
●The radial adults develop by
metamorphosis from bilateral larvae.
● The radial appearance of most adult
echinoderms is the result of a secondary
adaptation to a sessile lifestyle.
- Their larvae are clearly bilateral and even
echinoderm adults are not truly radial in their
● All 7,000 or so species of echinoderms are marine.
● They are divided into six classes:
Asteroidea (sea stars)
Ophiuroidea (brittle stars)
Echinoidea (sea urchins and sand dollars)
Crinoidea (sea lilies and feather stars)
Holothuroidea (sea cucumbers)
Example : Asterias
(Starfish@ sea star)
• Bear tube feet, which act
like a suction disc, part of
water vascular system.
• Mouth generally lower (oral)
surface of body, anus on
upper (aboral) surface.
• Lack spines.
• Hard endoskeleton is reduced.
• Five rows of tube feet, part of
water vascular system.
• Some of the tube feet around the
mouth are developed as feeding
• Attached to the substratum
• As a group, they use their
arms in suspension-feeding.
• The arms circle the mouth.
• This is the oldest and most primitive of all
classes of echinoderms.
• The sea lily is attached to the substratum by
a long stalk and thus sessile.
• Sea lily is star-shaped, and posses long
feather arms around the mouth (oral)
which is on the upper side, and has no
spine in its body wall.
(Sea urchin & sand dollars)
• Have no arms.
• Have 5rows of tube feet that
function in slow movement.
• Sea urchins are roughly
spherical while san dollars
are flattened & disc shape.
• Sea urchin has no arm, but has five
bands of tube feet.
• Its body is spherical, and is covered with
• The plates of the endoskeleton are
fused to form a rigid structure.
• The mouth is on the oral surface, and
the intestine is long and coiled.
Keyhole urchin's body is covered with skin, muscle
tissue, and short, fine spines that are used for
burrowing. Rows of tube feet extend through holes
forming the five "petals" on the top side.
• Distinct central discs, & the
arms are long & flexible.
• Their tube feet lack suckers
& move by serpentine lashing
of the arms.
Role of Echinodermata
• Star fish- Threaten the coral reef.
• Crown-of-thorns starfish (animal
• The only real predator of the dark starfish is
the triton. But triton are being over-harvested,
allowing the starfish to increase its numbers.
• Because the main food of the crown-of-thorns
starfish is coral, and the starfish population
continues to grow, the coral reef ecosystem is
being thrown out of balance.