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UNIT 7. INVERTEBRATES PART 2. ARTHROPODS. ARTHROPOD CHARACTERISTICS. Largest phylum of animals Most marine arthropods are crustaceans Body is segmented, bilaterally symmetrical Jointed appendages Exoskeleton made of chitin Molt (shed exoskeleton) small. CRUSTACEANS.

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unit 7

UNIT 7

INVERTEBRATES

PART 2

arthropod characteristics
ARTHROPOD CHARACTERISTICS
  • Largest phylum of animals
  • Most marine arthropods are crustaceans
  • Body is segmented, bilaterally symmetrical
  • Jointed appendages
  • Exoskeleton made of chitin
  • Molt (shed exoskeleton)
  • small
crustaceans
CRUSTACEANS
  • 68,000 known species
  • Most marine
  • Have gills
  • 2 pairs of antennae
  • Examples; copepods, barnacles, amphipods, isopods, krill, shrimp, lobster, crabs
biology of crustaceans
BIOLOGY OF CRUSTACEANS
  • Filter feeding
    • smaller crustaceans
    • Use bristles on appendages to gather particles
    • Use appendages in some for sucking and piercing
    • Stomach has chitinous teeth
  • Predators- decapods
    • Stomach is two chambered; digestive enzymes
    • Extracellular digestion; have anus
slide6
Open circulatory system
  • Gill exchange gases
  • Simple brain; but well developed sensory organs
    • Compound eyes
    • Keen sense of smell
    • Communicate with signals
reproduction life history
REPRODUCTION & LIFE HISTORY
  • Separate sexes
  • Internal fertilization
  • In decapods, females carry their eggs in their pleopods or swimmerets
  • Most have planktonic larvae
small crustaceans
SMALL CRUSTACEANS
  • COPEPODS: planktonic; use mouthparts to filter and capture food
    • Some parasitic
slide11
Barnacles- filter feeder; live attached to surfaces; body enclosed with heavy calcareous plates; have feathery filtering appendages called cirri
slide13

Beach hopper

  • AMPHIPODS- have a curved body that is flattened sideways
    • Under ¾ in
    • Head and tail typically curve downward
    • Ex: whale lice, beach hoppers
    • 5000 species
slide15

Fish lice

  • ISOPODS- similar in size to amphipods but have legs that are similar to each other and the body is dorsoventrally flat (flat back)
    • Pill bugs (land)
    • Fish lice
slide17
KRILL OR EUPHAUSIIDS- shrimp-like crustaceans; up to 2.5”; planktonic; head is fused with some of the body segments to form a carapace
    • Most filter feeders
    • Polar waters
    • Deep water
    • Main food source for large marine mammals
decapods
DECAPODS
  • Shrimps, lobsters, and crabs
  • 10000 species
  • Largest group of crustaceans
  • Five pairs of legs or perapods
    • 1st which is the heavier- the claw or cheliped
  • 3 pairs of maxillipeds- close to the mouth; used for eating
  • Well-developed carapace and encloses the cephlathorax (fused head and thorax)
  • abdomen
slide21
Shrimps and lobsters
    • Laterally compressed bodies with elongated abdomens
    • Shrimps are scavangers-some are cleaners
    • Some burrow in muddy bottoms
    • Lobsters are mostly nocturnal; scavangers and predators;
    • Hermit crabs (they are not true crabs) are scavangers; hide in snail shells
slide22

Mantis shrimp

Giant lobster

other marine arthropods
OTHER MARINE ARTHROPODS
  • HORSESHOE CRABS
    • 5 living species
    • Last of the class Merostomata; “living fossils”
    • Live on soft bottoms in shallow water
    • 5 pairs of legs
slide25
SEA SPIDERS
    • 4 or more pairs of jointed legs w/small body
    • Large proboscis w/mouth at the tip used to feed on small invertebrates
    • Cold water
slide26
Insects
    • 3 prs of legs as an adult
    • Rare in the sea
      • Most live on water’s edge or high tide mark
    • Marine water strider
lophoporates

LOPHOPORATES

BRYOZOANS, PHORONOIDS, LAMP SHELLS

lophophorate characteristics
LOPHOPHORATE CHARACTERISTICS
  • 3 groups
  • Have a unique feeding structure called the lophophorate which is a set of ciliated tentacles arranged in a horseshoe shape
  • Suspension feeders
  • No segmentation
  • Bilateral symmetry
  • U-shaped gut
slide29
BRYOZOANS- form colonies on seaweeds, rocks and other species
    • 4500 species; almost all marine
    • In phylum Ectoprocta
    • Colonies of individuals called ZOOIDS that secrete skeletons of various shapes
    • Lopophore is retractable
    • U-shaped gut ends in an anus outside the edge of the lophophore
slide33
PHORONOIDS-worm-like and build tubes
    • Horseshoe-shaped or circular lophopore
    • 20 species
    • Burrow in sand or attach tubes to hard surfaces
    • Very small
slide35
LAMP SHELLS OR BRACHIOPODS
    • 350 SPECIES
    • Shell w/2 valves that are dorsal and ventral to the body
    • Have a lophophore- w/2 ciliated and coiled arms
    • Attached to rocks or burrowed in soft sediment
arrow worms

ARROW WORMS

CHAETOGNATHS

characteristics of arrow worms
Characteristics of Arrow worms
  • About 100 species
  • Transparent; streamlined; fish-like fins and tail
  • Head has eyes, grasping spines and teeth
  • Up to 4”
  • carnivores
echinoderms

ECHINODERMS

5-WAY SYMMETRY

“spiny-skinned”

movie

echinoderm characteristics
ECHINODERM CHARACTERISTICS
  • Radially symmetrical-adults
    • Pentamerous – based on 5-parts
  • Bilaterally symmetrical- planktonic larvae
  • No head
  • No anterior/posterior end; no ventral/dorsal side
  • Refer to the oral and aboral side
  • Complete digestive tract
  • Well-developed coelom
slide42
Endoskeleton
  • Water-vascular system- waterfilled canals
    • Tube feet- muscular extensions of canals
      • Extended when filled with water- have muscular sacs called ampullae
      • Used for movement, attachment, and receiving chemical and mechanical stimuli
    • Madeporite- or sieve plate- in sea stars and sea urchins; on the aboral side; where water enters the water vascular system
biology of echinoderms
BIOLOGY OF ECHINODERMS
  • Radial symmetry = sedentary life style
  • Feeding and digestion- sea stars are carnivorous; they extend their stomach out through their mouth and excrete digestive enzymes; the food is then carried into the digestive gland and the stomach moves back into the body; if intestines are present, they are very small
    • Brittle stars- no anus; very simple guts
    • Crinoids- simple guts
slide44
Feeding and digestion cont.
    • Sea urchins and sea cucumbers have long coiled guts (sea urchins need this because they are herbivores and the sea cucumbers need this because they need to process sediment)
    • In all echinoderms, nutrients are passed in the coelomic fluid within the coelom
      • Also transports oxygen because they don’t have a circulatory system
      • Sea cucumbers have respiratory trees- which are thin, branched tubes that are connected to the gut and extend out to the anus
slide45
NERVOUS SYSTEM AND BEHAVIOR- have a nerve net- more complex actions than cnidarians though
  • REPRODUCTION AND LIFE HISTORY-
    • Separate sexes
    • External fertilization
    • Zygote develops into a ciliated larva
    • Some don’t have larva but brood their offspring in specialized pouches
    • Some reproduce asexually by the separation of the central disc or body into two pieces- REGENERATION
types of echinoderms
TYPES OF ECHINODERMS
  • 7000 KNOWN SPECIES- all marine
  • Bottom dwellers
  • 1. Class Asteroidea= sea stars
    • 5 arms that radiate from central disk
    • Amulacral groove= the radiating channels on the arms
    • Can move in any direction
    • Endoskeleton = interconnected plates of calcium carbonate creating very flexible arms; aboral surface may be covered with spines that are modified into pincer like organs called pedicellariae which helps to keep the surface clean
slide48
Asteroidea cont.
    • Most are predators of bivalves, snails, barnacles or other attached or slow moving animals
  • Class Ophiuroidea= brittle stars; 5 arms are very long and brittle
    • Most eat detritus and small animals
    • Tube feet don’t have suckers, used for feeding
    • No anus
    • Most species (2000)
slide49

Indian Sea Star

Anthenea crassa

slide51

Arctic Sea Stars eating

a Clam

Astropectin polyacanthus

slide52

Orange-banded Brittle Star (Ophiothrix)

Brittle star (Ophiocoma imbricatus)

slide54
CLASS ECHINOIDEA OR SEA URCHINS
    • Endoskeleton forms a round, rigid, shell-like test with movable spines and pedicellariae
    • Body forms a sphere
    • Mouth on bottom; anus on top
    • Graze on seaweeds and seagrasses
    • Have Aristotle’s Lantern- the set of jaws and associated muscles used by sea urchins to bite food
    • 1000 species
slide55

Purple Sea urchin’s test w/o

spines

Purple Sea Urchin with spines

slide56

Pencil Sea urchin

Banded Sea urchin

slide57
Class Echinoidea cont.
    • Heart urchins and sand dollars have flattened bodies and short spines
      • They are deposit feeders using tube feet and mucus to pick up particles
slide61
CLASS HOLOTHUROIDEA OR SEA CUCUMBER
    • Worm like
    • No spines and no obvious radial symmetry
    • Look stretched
    • Lies on one side where the 5 rows of tube feet are; oral and aboral surface on the ends
    • Endoskeleton has microscopic spicules
    • Deposit feeders; tube feet around mouth are modified into branced tentacles
slide62

Prickly red sea cucumber

  • Class Holothuroidea cont.
    • Defensive mechanisms
      • Secrete toxic chemicals in filament
      • Might expel the gut or other internal organs; this is called evisceration
slide63

Warty Sea cucumber

Orange sea cucumber

slide65
CLASS CRINOIDEA OR CRINOIDS
    • Suspension feeders
    • Feathery arms
    • 600 species of feather stars and sea lilies
    • Sea lilies are in deep water and attached to bottom
    • Feather stars perch and crawl in both shallow and deep water
    • An upside down brittle star with the amulacral grooves and mouth facing upward
slide66

Passion flower feather star

  • Class Crinodea cont.
    • Can have up to 200 arms
slide67

Feather star

Sea lily

hermichordates

HERMICHORDATES

PHYLUM

HERMICHORDATA

hermichordata characteristics
HERMICHORDATA CHARACTERISTICS
  • Share the same basic developmental characteristics of chordates and echinoderms
    • With chordates….
      • Dorsal, hollow nerve cord
      • Openings along the anterior part of the gut
    • With echinoderms…
      • Some have larvae
  • 85 known species
    • Acorn worms or enteropneusts- live free or in u-shaped tubes
slide71

Acorn worm

Acorn worm feces

slide74

Protochordates- invertebrate

Chordata- lack the backbone

  • 3 major groups or subphyla
    • Vertebrata
    • Urochordata
    • Cephalochordata
chordata characteristics
Chordata characteristics-
  • Single hollow nerve cord that runs along the dorsal length of the animal
  • Gill or pharyngeal slits
  • Notochord- a flexible rod for support that lies between the nerve cord and the gut
    • In vertebrata- surrounded or replaced by the backbone
  • Post-anal tail- a tail that extends beyond the anus
  • Ventral heart
tunicates
TUNICATES
  • Largest group of protochordates
  • Subphylum Urochordata
  • 3000 species; all marine
  • Sea squirts (Class Ascidiacea)
    • Saclike bodies; sessile; fouling organisms
    • Body protected by a tunic- a leathery gelatinous outer covering
    • Filter feeders; water flows through the mouth or incurrent siphon and out through the excurrent siphon
    • Ciliated, sieve-like sac- the pharynx
    • Can be colonial
slide77

Sea squirt

Larva and adult

  • Sea squirts cont.
    • Planktonic larvae have chordate characteristics; not the adult; known as tadpole larvae
      • Have gill slits, dorsal nerve cord, notochord and postanal tail
      • Has an eye as well
tunicates cont
Tunicates cont
  • Salps (Class Thaliacea)
    • Planktonic entire life
    • Transparent, barrel-shaped body with muscle bands for locomotion
    • Water through the incurrent siphon on posterior end
    • Warm water
    • Some colonial
tunicates cont79
Tunicates cont.
  • Class Larvacea or appendicularians
    • Planktonic tunicate
    • Body of tadpole larva throughout life
    • Delicate house for protection and to filter for food
lancelets
LANCELETS
  • 23 known species
  • Subphylum Cephalochordata
  • Body is laterally compressed and elongated like a fish; only up to 3 in long
  • Have all chordata characteristics throughout life except for backbone
  • Filter feeders; using gill slits to capture food
  • Live on soft bottoms