IB-202-5. 3-17-06. Cephalopods. Class Cephalopoda includes squids and octopuses Carnivores with beak-like jaws surrounded by tentacles. Foot modified to form siphon, tentacles and head. Closed circulatory system Well developed eye similar to vertebrate eye (lens, retina etc)
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(a) Octopuses are considered among the
most intelligent invertebrates.
(b) Squids are speedy carnivores with beaklike jaws and well-developed eyes.
Wednesday, 15 Jan., 2003, 16:50 GMT
Giant squid Architeutis dux
'attacks French boat'
….De Kersauson says his squid was
three times as big
…..two of the tentacles were blocking
…. the squid must have been seven or
eight metres (22 to 26 feet) long.
…. we weren't going to attack it with our
Wednesday, 28 September 2005, 05:42 GMT
Live giant squid caught on camera
Japan's Ogasawara Islands
(c) Chambered nautiluses are the only living cephalopods with an external shell. Have rudimentary eye without lens like a pin hole camera. Shell is chambered and put less dense ammonium chloride in chamber for flotation. Less dense than seawater.
Scorpions have pedipalps that are pincers
specialized for defense and the capture of
food. The tip of the tail bears a poisonous
Dust mites are ubiquitous scavengers in
human dwellings but are harmless except
to those people who are allergic to them
Web-building spiders are generally
most active during the daytime.
(exit for eggs)
Spiders digest there food outside of their body
They stab prey with their fangs, inject toxins and enzymes that digest tissues. Then they suck up the partially digested material as a fluid. Some of the enzymes are phospholipases that destroy cell membranes.
Thus spider bites can develop into lesions and tissue can become necrotic. Not sure why these enzymes can have such a long half life (in case of snakes give antivenom injections).
The insect body has three regions: head,
thorax, and abdomen. The segmentation
of the thorax and abdomen are obvious,
but the segments that form the head are fused.
Cerebral ganglion. The two nerve
cords meet in the head, where the
ganglia of several anterior segments
are fused into a cerebral ganglion
(brain). The antennae, eyes, and
other sense organs are concentrated
on the head.
Metabolic wastes are
removed from the
hemolymph by excretory
organs called Malpighian
tubules, which are out-
pocketings of the
Tracheal tubes. Gas exchange in insects is
accomplished by a tracheal system of branched,
chitin-lined tubes that infiltrate the body and
carry oxygen directly to cells. The tracheal
system opens to the outside of the body
through spiracles, pores that can control air
flow and water loss by opening or closing.
Insect mouthparts are formed from
several pairs of modified appendages.
The mouthparts include mandibles,
which grasshoppers use for chewing.
In other insects, mouthparts are
specialized for lapping, piercing, or
Nerve cords. The insect
consists of a pair of
ventral nerve cords
(d) Emerging adult
Cockroaches have a dorsoventrally flattened body, with legs
modified for rapid running. Forewings, when present, are
leathery, whereas hind wings are fanlike. Fewer than 40 cock-
roach species live in houses; the rest exploit habitats ranging
from tropical forest floors to caves and deserts.
Beetles comprise the most species-rich order of insects. They
have two pairs of wings, one of which is thick and leathery, the
other membranous. They have an armored exoskeleton and
mouthparts adapted for biting and chewing. Beetles undergo
Earwigs are generally nocturnal scavengers. While some
species are wingless, others have two pairs of wings, one of
which is thick and leathery, the other membranous. Earwigs
have biting mouthparts and large posterior pincers. They un-
dergo incomplete metamorphosis.
Dipterans have one pair of wings; the second pair has become
modified into balancing organs called halteres. Their head is
large and mobile; their mouthparts are adapted for sucking,
piercing, or lapping. Dipterans undergo complete metamorpho-
sis. Flies and mosquitoes are among the best-known dipterans,
which live as scavengers, predators, and parasites.
Hemipterans are so-called “true bugs,” including bed bugs,
assassin bugs, and chinch bugs. (Insects in other orders are
sometimes erroneously called bugs.) Hemipterans have two
pairs of wings, one pair partly leathery, the other membranous.
They have piercing or sucking mouthparts and undergo
Ants, bees, and wasps are generally highly social insects. They
have two pairs of membranous wings, a mobile head, and
chewing or sucking mouthparts. The females of many species
have a posterior stinging organ. Hymenopterans undergo com-
Termites are widespread social insects that produce enormous
colonies. It has been estimated that there are 700 kg of
termites for every person on Earth! Some termites have two
pairs of membranous wings, while others are wingless. They
feed on wood with the aid of microbial symbionts carried in
specialized chambers in their hindgut.
Butterflies and moths are among the best-known insects. They
have two pairs of wings covered with tiny scales. To feed, they
uncoil a long proboscis. Most feed on nectar, but some species
feed on other substances, including animal blood or tears.
Dragonflies and damselflies have two pairs of large, membran-
ous wings. They have an elongated abdomen, large, compound
eyes, and chewing mouthparts. They undergo incomplete meta-
morphosis and are active predators.
Grasshoppers, crickets, and their relatives are mostly herbi-
vorous. They have large hind legs adapted for jumping, two
pairs of wings (one leathery, one membranous), and biting or
chewing mouthparts. Males commonly make courtship sounds
by rubbing together body parts, such as a ridge on their hind
leg. Orthopterans undergo incomplete metamorphosis.
Stick insects and leaf insects are exquisite mimics of plants. The
eggs of some species even mimic seeds of the plants on which the
Insects live. Their body is cylindrical or flattened dorsoventrally.
They lack forewings but have fanlike hind wings. Their
mouthparts are adapted for biting or chewing.
Commonly called sucking lice, these insects spend their entire
life as an ectoparasite feeding on the hair or feathers of a single
host. Their legs, equipped with clawlike tarsi, are adapted for
clinging to their hosts. They lack wings and have reduced eyes.
Sucking lice undergo incomplete metamorphosis.
Fleas are bloodsucking ectoparasites on birds and mammals.
Their body is wingless and laterally compressed. Their legs are
modified for clinging to their hosts and for long-distance
jumping. They undergo complete metamorphosis.
Silverfish are small, wingless insects with a flattened body and
reduced eyes. They live in leaf litter or under bark. They can also
infest buildings, where they can become pests.
The larvae of caddisflies live in streams, where they make houses
from sand grains, wood fragments, or other material held to-
gether by silk. Adults have two pairs of hairy wings and chewing
or lapping mouthparts. They undergo complete metamorphosis.
Ghost crabs (genus Ocypode) live on sandy ocean
beaches worldwide. Primarily nocturnal, they take
shelter in burrows during the day. Note stalked eyes.
known as krill are
consumed in vast
quantities by whales.
The jointed appendages (modified legs)
projecting from the shells of these barnacles capture
organisms and organic particles suspended in
the water. Stand on their heads and glue
themselves to rocks with their antennae. Some form
Stalks like in picture, others not (example).
A short digestive tract runs from the
mouth on the bottom of the central
disk to the anus on top of the disk.
The surface of a sea star is
covered by spines that help
defend against predators, as
well as by small gills that
provide gas exchange.
Central disk. The central
disk has a nerve ring and
nerve cords radiating from
the ring into the arms.
Madreporite. Water can flow
in or out of the water vascular
system into the surrounding
water through the madreporite.
Digestive glands secrete
digestive juices and aid in
the absorption and storage
Branching from each radial canal are hundreds of hollow, muscular tube
feet filled with fluid. Each tube foot consists of a bulb-like ampulla and
suckered podium (foot portion). When the ampulla squeezes, it forces
water into the podium and makes it expand. The podium then
contacts the substrate. When the muscles in the wall of the podium
contract, they force water back into the ampulla, making the podium
shorten and bend.
Radial canal. The water vascular
system consists of a ring canal in the
central disk and five radial canals,
each running in a groove down the
entire length of an arm.
(a) A sea star (class Asteroidea)
(b) A brittle star (class Ophiuroidea)
(c) A sea urchin (class Echinoidea)
(d) A feather star (class Crinoidea)
(e) A sea cucumber (class Holothuroidea)
(f) A sea daisy (class Concentricycloidea)