Marine Invertebrates
A Summary CH7 pg 115
Kingdom Animalia
Divided into 2 GENERAL groups

Invertebrate (97% of animals)

Vertebrate
Phylum Porifera

Pore – bearers

Specialized cells (no tissues or organs)

Mostly marine, all sessile (attached)

Filter - feeders

Simple body plan w/tiny pores

Simple Body Plan

Specialized Cells

Ostia, on surface pulls water in

Osculum, large opening on top, water exits

Choanocytes, collar cells create current

Amebocytes, wandering cells secrete “skeletal” material

Spicule (calcareous or siliceous)

Spongin
Sponge Reproduction

Sexual or Sexual

Broadcast spawning

Some hermaphroditic

Early larval development occurs w/in sponge

Parenchymula larva
Diversity of Sponges

Encrusting

Glass sponges (Venus flower basket)

Boring sponges

Sclerosponges or coralline sponges

Siliceous spicules and spongin
Phylum Cnidaria (Coelenterates)
Characteristics

Radial Symmetry

Oral/Aboral Surface

Tentacles

Cnidocytes w/ nematocysts
Cnidarian Characteristics

Two basic forms

Polyp and/or medusa


Planula larva

Two tissue layers

Epidermis (outer)

Gastrodermis (lines the gut)

Mesoglea (gelatinous middle layer)
Types of Cnidarians
Class Hydrozoa
Class Scyphozoa
Class Anthozoa
Class Hydrozoa

Colony w/float

Portuguese – man – of – War (Physalia)
Class Scyphozoa

Rounded Bell

Moon Jelly (Aurelia)
Class Anthozoa

Polyp

Sea Anemone and coral
Phylum Ctenophora

Comb jellies

Radially symmetrical and gelatinous body

8 rows of ciliary combs

Colloblasts, sticky cells

Bilaterally Symmetrical Worms
Phylum Platyhelminthes

Flatworms

Central nervous system

Parasitic

Flukes and tapeworms
Phylum Nemertea

Ribbon worms

Circulatory system

Proboscis

Fleshy tube to entangle prey
Phylum Nematoda

Roundworm

Most parasitic
Phylum Annelida


Segmented worm

Earthworm and many marine worms

Closed circulatory system and gills

Trochophore larva

Polychaetes

Parapodia and setae
Phylum Sipuncula

Peanut worm
Phylum Mollusca

Soft – body covered by mantle

Secretes the shell (some)

Muscular foot (some)

Radula, ribbon of small teeth used to feed

Gills

Body Cavity
Types of Molluscs
Class Gastropoda
Limpet, abalone, nudibranch

Class Bivalvia o Clams, mussels, oysters

Class Cephalopoda o Octopus, squid, cuttlefish

Class Gastropoda

Class Bivalvia

Class Cephalopoda
Other Molluscs

Class Polyplacophora (chiton)

Class Monoplacophora (limpet)

Class Scaphopoda (tusk shells)
Biology of Molluscs

Feeding and Digestion

Nervous System and Behavior

Reproduction and Life History

Separate sexes and some hermaphrodite

Cephalopods (spermatophore)

Trochophore larva into veliger
Phylum Arthropoda

Largest phylum of animals, most on land

Subphylum Crustacea

Bilaterally symmetrical segmented body


Jointed appendages

Exoskeleton
 molt
Subphylum Crustacea

Specialized to live in water, most are marine

Copepods, barnacles, amphipods, krill, shrimp, lobsters, crabs, and hermit crabs (to name a few)

Gills and chitin skeleton

Specialized appendages

Two pairs of antennae

Feeding and Digestion

Filter feeders and scavengers
Nervous System

Compound eyes, keen sense of smell, statocysts

Communication

Reproduction

Separate sexes, gametes not shed into water

Nauplius larva
Other Marine Arthropods
Class Merostomata

Living fossils
Class Pycnogonida

Resemble true spiders
Phylum Lophorates

U – shaped gut

Bilateral symmetry

Coelom
Phylum Chaetognatha

Arrow worms

Smallest phyla, all marine

Important predatory plankton
Phylum Echinodermata

“Spiny – skin”

Radially symmetrical (5 parts)

Complete digestive tract, coelom, and an internal skeleton (endoskeleton)

Water – vascular system

Tube feet

Ampullae (muscular sac)


Madreporite
Types of Echinoderms

Class Asteriodea (sea stars)

Class Ophiuroidea (brittle stars)

Class Echinoidea (sea urchins)

Class Holothuroidea (sea cucumbers)

Class Crinoides (feather stars and sea lilies)
Biology of Echinoderms

Feeding and Digestion

Extending or inverting stomach

Nutrients transported by coelomic fluid

Nervous system and Behavior

Little known about nervous system

Reminiscent of nerve net

Turn over and camouflage themselves
Biology of Echinoderms

Reproduction and Life History

Separate sexes

External fertilization

Regeneration
Hemichordates: A “Missing Link”

Evolutionary link between the chordates

Chordates and echinoderms share embryo development

Dorsal hollow nerve cord

Pharyngeal gill slits

Acorn worms (U – shaped gut)

Chordates Without A Backbone
Phylum Chordata

Dorsal hollow nerve chord

Pharyngeal gill slits

Notochord

Post – anal tail
Phylum Chordata

Subphylum Urochordata (tunicate, sea squirts)

Subphylum Cephalochordata (lancelets)

Subphylum Vertebrata (bony or cartilage endoskeleton)