Exam 1 Marine Inverts

What are the characterisitics of the animal kingdom

Multicellular, heterotrophic, eukaryotes that lack a cell wall

the cells are organized and exhibit division of labor

What is a tissue

A group of cells arranged in a definite pattern or layer

the cells often perform a common function

come from embryonic layers called germ layers

What are germ layers

tissues that form in most early animal embryos

the precursors to differentiated adult tissues

Triploblastic animals have how many germ layers

3 - ectoderm, endoderm, mesoderm

Diploblastic animals have how many germ layers

2 - ectoderm and endoderm

What makes an animal triploblastic

Bilateral symmetry, humans

What makes an animal diploblastic

always has radial symmetry, cnidaria, comb jellies

What two unique tissue types do animals possess

Nervous tissue and muscle tissue

What does the nervous tissue do for animals

Neurons & supporting cells, functions to conduct signals

What do muscle tissues do for animals

functions in movement via contraction, contraction results from the interaction of actin & myosin

What are key characteristics of phylum placozoa (placozoans)

very small animals (1-3mm)

plate animals

smallest genome of any animal

lack muscle, nerves, internal gut

anatomically & histologically simple (4-6 cell types)

have dorsal and ventral epithelia but no symmetry or body polarity

move by ciliary gliding

feed on microbial / algal films

form a temporary digestive cavity from ventral epithelium

asexual reproduction by fission / frag

sexual reproduction is poorly understood

What are the key characteristics of Phylum Porifera

originated early in the history of animals

may be paraphyletic & ultimately may be split into different phyla

no nervous tissue or muscle

some undergo gastrulation to form layered embryo

tissues are very simple (if present)

What are the habitats and ecological role of poriferans

sessile

all aquatic marine, few freshwater

filter feeders - vast majority, some carnivores

size range: few mm - 1m

Some species in our local area

Red beard sponge (Clathria prolifera)

Sun sponge (Hymeniacidon)

boring sponge (Cliona celata)

What is the aquiferous system with the path of water flow

ostia —> spongocoel —> osculum

How does the aquiferous system work

Cylindrical cell that forms a channel

pass through all 3 layers

comprise ostia

What are the layers of the Poriferan body wall

Pinacoderm (outer)

Mesohyl (middle)

Choanoderm (inner)

What are some characteristics about the pinacoderm

composed of pinacocytes

have syncytial outer covering

What are some characteristics about the mesohyl

Gelatinous matrix containing skeletal elements & cells

Amoeboid cells (archeocytes and cells that produce skeletal elements)

Skeletal elements are spongin fibers, spicules which could be calcareous or siliceous

How is the hexatinellid sponge composed

skeleton composed of fused 6-rayed siliceous spicules

What are some characteristics of choanoderm

layer of flagellated cells called choanocytes

responsible for water flow through the sponge

How does choanocyte function of water movement and feeding

particles are drawn into sponge via ostia

water passes between collar microvilli

particles thought to be trapped by the collar, but may not be correct

particles on plasma membrane are taken in by phagocytosis

Carnivorous sponge

found in the deep sea

has a stalk and filaments

prey is captured using spicules on filament

What are the 3 morphological types of poriferas

Asconoid

Syconoid

Leuconoid

What are characteristics of asconoid

spongocoel present

relatively low SA/V

What are characteristics of Syconoid

spongocoel present

body wall folded

higher SA/V

What are some characteristics of Leuconoid

spongocoel absent

many small flagellated chambers

highest SA/V

What is SA/V

Ratio of choanoderm surface area to volume of water in spongocoel or flagellated chamber

What is the reproduction strategie of poriferans

may reproduce sexually or asexually

with sexual reproduction: species may be hermaphrodites or gonochoristic, no gonads.

What is the generalized scheme for sexual reproduction

sperm released into water

enter female sponge

sperm trapped by choanocyte which becomes a transfer cell

fertilization in situ - female broods developing embryo

larva is released

settles & reorganizes into juvenile

How does asexual reproduction in poriferans work

budding or fragmentation

gemmules: in freshwater sponges, seasonal to help survive harsh conditions

Regeneration in poriferans

the ability to re-grow injured or missing structures

aggregation experiments - wilson (early 1900s)

• demonstrated aggregation AND that the process is species-specific.

What defenses do sponges have

spicules

bioactive compounds often produced by symbiotic microbes

may be antiviral, antimicrobial, antitumor, or anti-inflammatory properties

Characteristics of Class Calcarea

spicules of calcium carbonate (CaCO3)

all 3 morphologies (asconoid, syconoid and leuconoid)

What are the characteristics of Class Hexactinellida

6 rayed siliceous spicules (glass sponges)

syconoid or leuconoid in structure

no pinacoderm, syncytial outer layer

spicules with fiber optic properties

What are the characteristics of Class Demospongiae

90% of sponges, includes all freshwater, sponges

spongin fibers, siliceous spicules or both

all leuconoid in structure W

What are the characteristics of Class Homoscleromorpha

spongin skeleton is absent

spicules similar in size

What are the key characteristics of Ctenophores

Majority are pelagic, some benthic

all marine

surface waters to depth of at least 7000m

comprise a major portion of plankton biomass

150-250 species

possess true tissues (eumetazoan grade)

biradial symmetry

body has 2 layers separated by gelatinous material

diploblastic with possible triploblastic

have muscles and a netlike nervous system

swim using structures called ctenes

plates of compound cilia that occur in rows along the body

have special organelles that produce an adhesive (used to capture prey)

have colloblasts

Characteristics of Order Cydippida

Ovoid bodies with branched tentacles covered with colloblasts

typically 8 rows of ctenes

What are the characteristics of order lobata

have a pair of muscular lobes extending from the mouth

tentacles are very small

ciliated surfaces drive prey towards the mouth

what are the characteristics of order beroida

no appendages

macrocilia help sweep prey into mouth

mouth is highly distensible - may form by tearing open

What are the characteristics of Order Platyctenidia

benthic/ epibenthic

comb rows greatly reduced

flattened, creep along substrate

what are the characteristics of order thalassocalcida

pelagic - extremely fragile

one species

somewhat medusa like morphology