10.1 Introduction to Crustaceans The Lobster

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1 Chapter 10

2 10.1 Introduction to Crustaceans The Lobster Arthropods phylum Arthropoda, meaning jointed feet Characteristic moveable limbs Outer skeleton is its exoskeleton Made of chitin, type of carbohydrate Varies in flexible to hard in different arthropod species Functions as protective as well as a place for muscles to attach Diverse in appearance, some scientist want to divide them in different classes, subphya, or separate phyla

3 Crustacean Features Crustaceans animals with hard outer covering Bilateral symmetry, divided into two main segments Cephalothorax head and chest regions Abdomen tail (if present) Carapace exoskeleton that covers the head Lobster, crabs, and shrimp have 5 pairs of legs Referred to as decapods Claws that are used in food-getting are 1 st pair and the 4 other pair are for walking Head has 2 eyes, 2 pairs of antennae, special mouthparts used for feeding Some crustaceans can glide along the sea floor by using a small paddlelike appendages swimmerets located under the abdomen Crustacean grow by shedding their exoskeleton each year in a process called molting

4 The Lobster Two common lobster species Northern Lobster Homarus americanus has 2 lg. claws Live in rocky subtidal zone Found from Labrador to Virginia Spiny Lobster Panulirus argus No lg. claws Found in waters of Florida, Gulf of Mexico, and California Lobsters are aggressive, often fight amongst themselves Lobsters can sacrifice a body part to escape and regenerate the appendages

6 Structures and Life Activities of Lobsters Lobsters are predators Feed on other invertebrates Mussels Sea urchins Scavenge on dead animals Food digested in a one-way tract Mouth Esophagus Stomach Intestines Breathe through gills, under carapace Each gill attached to the upper end of walking legs Oxygen & nutrients transport around lobster s body in its blood Blood is blue in color due to pigment hemocyanine contains copper which binds oxygen Blood pumps through the body by a one-chamber heart, aided by body muscular contraction No capillaries connecting arteries and veins, blood just passes through tissue space

7 Nervous system enable a variety of responses Eyes on movable stalks Two pairs antennae actively feel out environment Impulses from receptors carried by sensory nerves to brain, or cerebral ganglia Responses carried out when brain send impulses back via ventral nerve cord to muscles Lobster reproduce sexually Fertilization internal, development external Sperm deposited in females abdomen Eggs are released and carried by female on swimmerets for almost a year before hatching Embryo go through larval phase, float as part of plankton population, molting as they grow into adult form

10.2 Another Important Crustacean: The Crab The Crab fiddler crab (Uca) digs tunnels in the sand along shore Retreat into tunnel and plug up entrances

8 10.2 Another Important Crustacean: The Crab The Crab fiddler crab (Uca) digs tunnels in the sand along shore Retreat into tunnel and plug up entrances Gets its name for its large claw resembles the arm position of a person playing the fiddle Male has one lg. and one sm. claws Female has two sm. claws

9 Mole crab Emertia lives in turbulent surf zone along sandy beaches Has smooth streamlined body that diminishes impact of waves, allows crab to burrow and move efficiently through swirling mixtures of sand and water Has featherlike antennae, used to capture microscopic organisms Hermit crab Pagurus longicarpus born with soft abdomen, lacks exoskeleton For protection hermit crab finds empty snail shells to live in Inhabit shallow coastal waters Scavenge on particles of food As it increases in size it outgrows old shell and finds a lager one

Spider crab Libinia emarginata slow moving, has no paddle appendages Pointed legs used for crawling along ocean bottom Algae and barnacles have time to attach and grow on their backs Inhabits

10 Spider crab Libinia emarginata slow moving, has no paddle appendages Pointed legs used for crawling along ocean bottom Algae and barnacles have time to attach and grow on their backs Inhabits Atlantic and Pacific waters Scavenge for food particles Biggest crab in the ocean is the giant spider crab Macrocheira kaempferi Found in deep waters off Japan Leg tip to leg tip 4 meters in width

11 Structures and Life Activities of Crabs Crabs body is divided into segments covered by carapace are the Cephalothorax - Abdomen small flat, between walking legs on ventral side Shape of abdomen tells the sex of the crab Female has a U-shaped abdomen Male has a V-shaped abdomen Crabs eat mainly dead plants and animal matter, graze on algae and some are predatory Claws are for tearing and shredding food One-way digestive tract Mouth, esophagus, stomach, & intestines Breath through gills Two eyes and antennae Well-developed nervous system Female carries a mass of eggs between her abdomen and thorax, male fertilizes eggs internally Embryos develop exsteranally

12 10.3 Diversity Among Crustaceans: The Shrimp and Others The Shrimp sm. Version of the lobster Gulf shrimp Penaeus duorarum grow up to 17 cm long, seafood industry Smaller common shore shrimp Palaemonetes vulgaris lives among the grasses and seaweeds in salt marshes Smallest shrimp Periclimenes survives by eating parasites and are found on the skin of reef fish a symbiotic relationship Mantis shrimp Squilla empusa largest of all shrimp grows to 25 cm long Burrow in the sand or mud, spear its prey

13 Copepods and Krill Copepod is the most abundant crustacean Over 1000 species ½ cm long Eats mainly diatoms Important part of zooplankton community, vast bulk of the base food chain Reproduce sexually Krill is a shrimplike animal Grows to 5 cm long Most live in Antarctic water Planktonic animal, eats diatoms, and floats on ocean surface in lg. masses Principal food source for filter-feeding whales

14 Amphipods and Isopods These crustaceans are found near the edge of the sea- amphipods under rocks and debris in the intertidal zone Scud Gammarus are bottom dwellers Live in wet sand East and West coast Beach flea Talorchestia Use seaweed for cover and food

15 Sea roach Ligua resemble a pill bug Swim, crawl in coastal waters among the seaweeds Feed on algae Active at night & hides during the day Flattened bodies and 7 pairs of legs isopods Can live attached to gills and skin of fish such as cod and halibut

The Barnacle Often mistaken for a mollusk Acorn or rock barnacle Balanus lives in the upper intertidal zone, attached to rocks and hard surfaces

16 The Barnacle Often mistaken for a mollusk Acorn or rock barnacle Balanus lives in the upper intertidal zone, attached to rocks and hard surfaces Overlapping sharp calcium carbonate plates protect the animal inside Attach to almost any substrate, ship s hull, whale s skin A type of encrusting organism

17 Structures and Life Activities of Barnacles Barnacle s body id actually folded up within its shell so that its appendages can protrude from the opening When tide comes in barnacle opens its shell plates and extends its six pairs of feathery appendages cirri Cirri whip about catching phytoplankton ad other food particles and brings it to its mouth Filter feeders Food digested in a one-way tract Mouth, stomach, and intestine O2 and CO2 are exchanged across barnacle s skin membrane At low tide when barnacle is exposed to air its overlapping plates shut to keep animal from drying out

Barnacle contains both ovaries and testes, hermaphrodite Self-fertilization does not occur Mating occurs when penis of one barnacle is inserted into a neighboring barnacle Fertilization occurs inside

18 Barnacle contains both ovaries and testes, hermaphrodite Self-fertilization does not occur Mating occurs when penis of one barnacle is inserted into a neighboring barnacle Fertilization occurs inside the barnacle, and fertilized eggs develop into swimming larvae that is shed into the water When larvae come into contact with suitable substrate they attach to it by secreting glue from a special gland and develop into an adult

19 10.4 Diversity Among the Arthropods The Horseshoe Crab Limulus polyphemus arthropod often mistaken for a crab Lacks antennae & mouthparts Has 6 pairs of legs More closely related to spiders and scorpions Placed in its own class, Merostomata Inhabits waters along Atlantic and Gulf coast and Asian Pacific coast Searched for food in the mud, preying on sm. Mollusks and crustaceans Has 4 eyes, two simple and two compound eyes, on top of carapace Compound eyes contains many visual units which are grouped together for better vision

20 Structures and Life Activities of Horseshoe Crabs Legs are on the underside of horseshoe crab First pair is set with pinching claws cheliceras Other five are walking legs In male fist claw is shaped like boxing glove Body and legs are covered by carapace Behind the legs are numerous overlapping membranes, these are the book kills used for breathing and locomotion Spiked tail or telson is not used as a weapon It is used for locomotion and when tossed on its back by a wave it uses it as a lever to flip itself over

22 Life Cycle of the Horseshoe Crab In late spring at high tide, thousands of horseshoe crabs invade the sandy beaches and marshes Females carrying the smaller male clutched to their backs at the hightide mark dig holes in sand and lay hundreds of tiny pale green eggs Males still attached to female externally fertilize the eggs and then cover the eggs with sand After two weeks eggs hatch and tiny juveniles carried out to sea by the tide swim away. Within months they develop spiked tails and other characteristics of adults Horseshoe crab reaches sexual maturity in about eight yrs. During its period of growth it undergoes many molts, sheading its outer shell and growing another These old shells are often found on the beach and mistaken for dead crabs Fossils of the horseshoe crab show that this animal has not changed very much in 400-million-years For this reason the horseshoe crab is often called a living fossil

23 Marine Insects Some inhabit the high salinity water and others are found in the salt marsh Biting insects live in the salt marsh and inland bays All possess chitinous exoskeleton & jointed appendages Only have 3 pairs of legs and 3 body segments, head, thorax and abdomen Have just 1 set of antennae and 1 pair of eyes Placed in the class Insecta Most familiar is the marsh mosquito Greenhead fly Sad fly or no-see-um These insects often inhabit inland estuaries where there is less wave impact and provide flat surfaces for insects to lay their eggs Eggs can develop into larvae which then develop and hatch into adults

Name Date Period Crustaceans- Chapter 10 Guided notes

Name Date Period Crustaceans- Chapter 10 Guided notes 10.1 Introduction to Crustaceans The Lobster Arthropods phylum Arthropoda, meaning Characteristic Outer skeleton is its Made of, type of carbohydrate