Transcript Arthropods - St. John the Baptist Diocesan High School

ARTHROPODS
Crabs, Lobsters, Shrimp, Barnacles,
Horseshoe Crabs and More!
ARTHROPOD CHARACTERISTICS
 Phylum: Arthropoda (Arthro =
jointed, Pod = foot)
 Invertebrate with an external
skeleton, jointed appendages, and
a segmented body
 Over 80% of all animal species are
Arthropods!
Estimate: 1,000,000 spp. arthropods
1,190,000 spp. animals
~ 84% of all animal species are arthropods
ARTHROPOD CHARACTERISTICS
 The arthropod body plan
consists of repeated
segments, each with a
pair of appendages
 Open circulatory system
 External Skeleton
(exoskeleton)
 Skeleton does not grow
with them, so they must
molt
OPEN CIRCULATORY SYSTEM
 Blood is not contained in vessels
 All the organs are constantly bathed in hemolymph,
a combination of blood and lymph
 Blood is drawn in to the heart through holes called
ostia, then pumped out again to circulate through
the tissues and return again to the heart.
MOLTING
 Exoskeleton cannot
grow, so they
replace their
exoskeletons by
molting, or shedding
the old exoskeleton
after growing a new
one that is not yet
hardened.
 Molting Time Lapse
MOLTING (STEP 1)
Secretion of
"molting
fluid" to
dissolve old
endocuticle.
MOLTING (STEP 2)
New cuticle formed
under old
exocuticle.
Break out of old
cuticle
Old cuticle breaks
at line of weakness
MOLTING (STEP 3)
Inflate with water/air
to increase size while
skeleton soft,
–but soft skeleton
& gravity limit size;
•Hardening of new
exocuticle.
•Vulnerable until new
skeleton hardens
GROWTH STAGES
Arthropod passes thru
3-20+ growth stages
in life cycle.
Some stop molting as
adults (insects, most
spiders)
Some continue to molt
(crayfish, tarantulas)
REPRODUCTION IN MARINE
ARTHROPODS
 Sexes are typically separate
 Some species are hermaphroditic (barnacles)
 Internal fertilization: males have specialized
appendages to transfer sperm to females
Chelicerates
(arachnids)
MARINE
ARTHROPODS
Crustaceans
CHELICERATA (ARACHNIDS)
Includes
spiders, mites,
scorpions,
ticks and
horseshoe
crabs—4 pairs
of legs (8 legs
total)
CHELICERATA
HORSESHOE CRABS
• Common of f of the Atlantic and Gulf coasts
• Large dorsal carapace bearing compound eyes
• Abdomen terminates in a long tail called the telson; used to
turn the animal right side up
• Possess a series of gill plates called book gills
Horseshoe
Crab Facts
CRUSTACEANS
Includes
lobsters, crabs,
crayfish,
barnacles, and
shrimp
Most are aquatic
5 pairs of
walking legs
COPEPODS (SMALL CRUSTACEANS)
The smallest & most
abundant crustacean
Marine zooplankton
Elongated antennae
Filter feeding mouth
BARNACLES
 Usually live attached to a surface, including crabs and whales
 Surrounded by thick calcium plates
 Lie on their backs and use feathery appendages called cirri
(attached to legs) to filter feed
BARNACLES AND WHALES
 Symbiotic Relationship
 Barnacles get a place to
live, protection from
predators, and feed on
plankton as the whale
swims
 Whales are typically not
bothered, and the
barnacle “suit of armor”
often protects them
DECAPODS
 5 pairs of legs (10 total), first pair are claws
 Lobsters, Crabs, Shrimp
 Largest groups of crustaceans (and very delicious!)
JAPANESE SPIDER CRAB
 Largest crustacean in the world!
 Up to 12 feet wide from claw to claw
MANTIS SHRIMP
 Highly advanced eyes
 Modified claws to pack a deadly punch!
 True Facts about the Mantis Shrimp
DEEP SEA SHRIMP
Spews a Bioluminescent Mucus Cloud!
How do you know this is a crab
and not a spider?
Fiddler Crab Waving
CRAYFISH DISSECTION
 External Anatomy (Start at 4:00)
 Internal Anatomy