Marine Inverts Exam 3

Phylum - Mollusca

Mollusks

Class - Gastropoda

class of mollusk, snails and nudibranchs

Class - Scaphopoda

class of mollusk, tusk shells

Class - Bivalvia

class of mollusk, clams

Class - Cephalopoda

class of mollusk, squids and octopus

Class - Monoplacophora

class of mollusk, not in the salish sea, deep-sea cap shells

Superclass - Aplacophora

superclass of worm-like mollusk, not in the salish sea, class solenogastres and caudofoveata

Class - Polyplacophora

class of mollusk, chitons

General Mollusk Architecture

Circumpharyngeal brain

brain surrounds gut, often ring-llike, paired ventral nerve cord

Mantle

secretes shell

open circulatory system

with a heart and dorsal blood vessel, blood diffuses into organs

ctenidium

gills

nephridium

kidney

nephridopore

expels metabolic waste from kidney

gonopore

expels gametes

radula

feeding device, file-like, scapres stuff

one way gut

mouth and anus

Class - Polyplacophora architecture

like general mollusk but with no head, ctenidium are a ring around the foot, 8 plates (valves) instead of a shell

girdle

surround valves on the side

Class - Gastropod architecture

like general mollusk but undergoes torsion → general architecture is flipped 180,

gills, anus, and mantle cavity on the anterior side, + crop

crop

extra digestive organ, mechanical digestion

Class - Bivalvia architecture

like general mollusk but, hinged shell, labial palps instead of radula, + siphons

Class - Scaphopoda architecture

like general mollusk but stretched vertically, conical shell, no heart and no gills, captacula for feeding

Class - Cephalopoda architecture

like general mollusk + ganglia for complex movement, beak, cecum, 3 hearts (2 branchial 1 systemic), crop, siphon

cecum

digestive sack

branchial hearts

move blood past gills

systemic heart

central heart that pumps oxygenated blood to the body

Class - gastropoda feeding

diverse → herbivore, carnivore, scavengers, deposit feeders, suspension feeders, parasites

Class - Scaphopoda feeding

use captacula to capture food in sediment, very small

Class - Bivalvia feeding

suspension and deposit using labial palps, symbiotic algae

Class - Cephalopoda feeding

carnivores

Class - Polyplacophora feeding

mircophagous graxers (algae and small animals)

Class - Aplacophora feeding

caudofoveata - deep sea deposit feeding, solenogastres - predators on cnidarians

Mollusk Reproduction and Development

generally dioecious (some monoecious nudibranchs), broadcast and free spawning in bivalvia, polyplacophora, scaphopoda, bopulation in gastropoda and cephalopoda, trocophore larva

Gastropoda subclasses

Clade Vetigastropoda*

- primitive

- most with slits or holes, some bilateral symmetry of organs

Clade Patellogastropoda*

- true limpets

Clade Caenogastropoda*

- caen = recent

- 60% of all gastropods (torsion, single auricle, single pair of gill leaflets

Clade Heterobranchia*

- different gills, nudibranchs

- detorsion, pulmonates, opisthobranchs, hermaphroditic

Nudibranch architecture

Dorid nudibranchs

anus on midline and surrounded by plumose gills

Aeolid nudibranchs

anus to the side, cerata with branches off digestive gland

Dendronotid nudibranches

cerata or rhinophores branched, rhinophores surrounded by sheath

Arminacean nudibranchs

oral veil, thickened mantle with extended margins and longitudinal ridges

Cephalaspideans

Bubble snails

• Head covered by broad

sheet of tissue (shield)

• No tentacles or

rhinophores

• Sides of foot rolled up

• Shell partially or

completely interna

Anaspidians

sea hares, one ctenidium, eat algae usually off of eelgrass, large mantle cavity on right side

Phylum Mollusca - Class Bivalvia - Macoma nasuta

bent because it burrows and sits horizontally, surface deposit feeder

Phylum Mollusca - Class Bivalvia - Pododesmus cepio

jingle shell, asymmetrical valves (1 bigger and 1 smaller)

Phylum Mollusca - Class Bivalvia - Crassostrea gigas

japanese oyster

Phylum Mollusca - Class Bivalvia - Chlamys hastata

clam, sometimes covered by sponges, eye spots, byssal threads, can swim, single adductor muscle, rough ridges spread out

Phylum Mollusca - Class Bivalvia - Chlamys rubida

same as hastata but rudges are smoothers and closer together

Phylum Mollusca - Class Bivalvia - Clinocardium nuttallii

coggles, live shallow in sediment, use foot to do underwater cartwheels as escape response

Phylum Mollusca - Class Bivalvia - Saxidomas gigantea

butter clam, circular ridges, can live for 20 yrs

Phylum Mollusca - Class Bivalvia - Hinnites giganteus

scallop, eye spots, attaches to rocks

Phylum Mollusca - Class Bivalvia - Mytilus californianus

larger with a rougher shell, mussel

Phylum Mollusca - Class Gastropoda - Triopha catalinae

Phylum Mollusca - Class Gastropoda - Archidoris odhneri

dorid nudibranch, eat sponges

Phylum Mollusca - Class Gastropoda - Onchidoris bilimellata

eats barnacles, vary in color

Phylum Mollusca - Class Gastropoda - Calliostona ligatum

Phylum Mollusca - Class Gastropoda - Diadora aspera

keyhole limpit, not a true limpit because of hole at its apex

Phylum Mollusca - Class Gastropoda - Haliotis kamtschatkana

algal grazers → red coraline algae

Phylum Mollusca - Class Gastropoda - Nucellaa lamellosa

Eats barnacles and small mussels, creates egg cases after reproducing, direct development, predator, variety of shells based on env.

Phylum Mollusca - Class Gastropoda - Hermissenda crassicornis

predatory on many dif things

Phylum Mollusca - Class Gastropoda - Ceratostoma foliatum

grazer on algae and invertebrates, pointy tooth near mouth, leafy shell shape

Phylum Mollusca - Class Gastropoda - Lottia persona and Scutum

persona = taller and with a solid band on the bottom, scutum = shorter with a striped band on the bottom

Phylum Mollusca - Class Gastropoda - Littorina sitkana

periwinkle, 1cm across and bulbous, non-checkered shell (scutulata is smaller with a checkered shell), upper intertidal algal grazer

Phylum Mollusca - Class Polyplacophora - Mopalia muscosa

grazes at hightide, hides under rocks at low tide, mossy chiton

Phylum Mollusca - Class Polyplacophora - Cryptochiton stelleri

gumboot chiton, large, girdle completely covers 8 plates

Vertical zonation of the rocky intertidal

acorn baracles → mussels and goose barnacles → anemones → sea stars and macroalgae

upper intertidal → lower intertidal

Upper intertidal

community composition controlled mostly by physical stress (desiccation, heat, etc.), hosts the most tolerant species

Lower intertidal

Community composition controlled mostly by biological stress (competition and predation). Hosts the best competitors for space, or excludes organisms based on predation, species less tolerant of heat and desiccation

Brachiopoda

Lamp shells with lophophores dominated the Paleozoic (248 to 545 million years ago), used to be very diverse, but declined greatly during extinction events, especially the Permian-Triassic, suspension feed with lophophore

Articulate brachiopods

2 valves and a hinge

Inarticulate brachiopods

2 valves but no hinge

Brachiopoda architecture

peddicle

attaches brachiopod to substrate

diductor muscle

Keeps valves together

Brachiopod reproduction and development

typically dioecious broadcast spawners (some brooding and viviparous)

inarticulate - long-lived planktonic larva

articulate - short-lived planktonic larva

Phylum Brachiopoda - Terebratalia transversa

Phylum - Arthropoda

bilateral symmetry, segmentation (always in embryos, segments often fuse into tagmata (larger body parts)), jointed limbs, exoskeleton (molt to grow), 80% of animal species, open circulatory system with heart

molting

energy intensive, exoskeleton cuticle is secreted by epidermis → epidermis secretes a fluid that separates the epidermis from the exoskeleton → new cuticle/exoskeleton is secreted → an enzyme that breaks down the old exoskeleton is secreted → the arthropod emerges

cuticle

made of a glucosamine polymer

Arthropoda subphyla

Uniramia, Chelicerata, Crustacea

Subphyla - Uniramia

insects, 3 head appendages (antennae, mandibles, maxillae), 3 tagmata (head, thorax, abdomen), unbranched appendages, 1 pair of antennae

Subphyla - Chelicerata

spiders, scorpions, horseshoe crabs, sea spiders (pycnogonids), 2 head appendages (chelicerae (fangs) and pedipalps), 2 tagmata (cephalothorax, abdomen), unbranched appendages, no antennae

Subphyla - Crustacea

crabs, lobsters, shrimp, 5 head appendages (1st and 2nd antennae, 1st and 2nd maxillae, and mandibles), 3 tagmata (head, thorax, abdomen), unbranched appendages, 2 pairs of antennae

Subphyla Chelicerata - Order Xiphosura

horseshoe crabs, 4 species, ~80 fossil species, 2 tagmata, tail called a telson, book gills on abdomen, blood coagulates in the presence of bacteria → used in biomedicine

Subphyla Chelicerata - Class Pycnogonida

~1300 species, small, breath through their legs via diffusion, 4-6 pairs of walking legs, males have an oviger (divot on their dorsal side) to carry eggs, have palps and a proboscis

Physical processes afecting subtidal ecology

temperature and currents

Upwelling

winds from the North + the coriolis effect bend water offshore → surface water pushed out → cold deep nutrient rich water moves to the surface along shore

provides nutrients for phytoplankton but can sweep planktonic larva offshore

Currents

Wave action influences food supply and larval recruitment and can influence the bottom community (kelp vs. suspension feeders). Density and diversity of organisms increase with increasing flow → more habitat heterogeneity as features create microenvironments of lower or higher flow, bringing nutrients to filter feeders → more biomass; predation or grazing pressure can be interrupted and relieved

Light

f(water depth) and f(bottom orientation), horizontal orientation = more light vertical = less light, horizontal = macroalgae dominated, vertical = invertebrate dominated. inverts arent outcompeted on vertical walls for space

Herbivory

urchins and chitons → grazers, can create urchin barrens and impact community structure by controlling macroalgae populations

Predation

Top-down controls → sea otter eats urchin → more macroalgae because grazing strain has been relieved, Orca eats sea otter → less sea otter → less predation on urchins → more urchins → more grazing → less marcoalgae

Competition for space

inverts vs. macroalgae → vertical vs. horizontal → inverts lose when there is a lot of light

Positive interactions

foundation species increase diversity (mussels, kelp, etc.) by adding to habitat complexity, species can modify the habitat fascilitating colonization by new species etc. → urchins make kelp biomass available for deposit feeders

Phylum Arthropoda - Subphylum Crustacea

classes: Branchiopoda, Remipedia, Cephalocarida, Thecostraca, Copepoda, Ostracoda, Malacostraca

Subphylum Curstacea - Class Malacostraca

crabs, lobsters, shrimp

Subphylum Curstacea - Class Thecostraca

barnacles

Class Thecostraca life cycle

Class Thecostraca architecture

Subphylum Crustacea - Class Copepoda architecture

many eating appendages

Prosome

portion of the copepod with appendages