Mollusca

General Characteristics

• Protostomes (1st opening mouth 2nd anus)
• Most are Marine
• Ex: snails,oysters,squid,and octopus
• bilaterally symmetrical

Mollusca Anatomy

Head-Foot

The region of mollusc that is a big muscular mass that contains feeding, cephalic sensory,locomotor organs. Used for movement (foot) connected to the head (real head and brain)

Mollusca Anatomy

Visceral Mass

Mollusca Anatomy

Mantle

special organ that secretes the calcium carbonate shell and is a thin flap of tissue that curves all the way around the animal that forms a cavity to protect organs.

In bi-valves the animal lives inside the mantle and there is a mantle cavity (space) in between the mantle and the visceral mass. 

Mollusca Anatomy

Shell

 made of calcium carbonate exo-skeleton

First layer (innermost pearl-like shiny layer) of shell called nacre is made primarily out of calcium-carbonate with some protein.

The middle layer is the prismatic built out of calcium carbonate with some protein.

The outermost layer is the periostracum is made out of protein to protect inner layers and are thicker in freshwater molluscs because of the pH (acidic). Every year the mantle lays out two new outer layers as it grows. The inner layer is laid out to make the shell thicker.

Mollusca Anatomy

Open Circulatory System

Blood is free flowing in body cavity it is not always contained in vessels. It just washes through the animal and through the heart via holes (ostia)

Mollusca Anatomy

Ostia

Mollusca Anatomy

Kidneys

Mollusca

Pearl Production

Mollusca Anatomy

Radula

a series of teeth that act like a belt sander in the mouth to break down pieces of food

Bi-valves dont have this

Mollusca Anatomy

Gills

Mollusca

Reproduction

most have indirect reproduction: larvae don’t look like adult

trochophore:  first stage larvae

 veliger: second larval stage always have beginning of a shell and a foot a way molluscs can move themselves around because they cant move when they are adults.

• Caudofoveata and Solenogastres
• Monoplacophora
• Gastropoda
• Bivalvia
• Cephalopoda

Mollusca Classifications

Caudofoveata and Solenogastres

not much is known about them

only molluscs that don't have shells

Mollusca Classification

Monoplacophora

• have a single shell

Mollusca Classfication

Polyplacophora (chitons)

• Shallow water animals or stick to rocks
• have a series of eight plates

Mollusca Classification

Scaphopoda

tusk shells: look like tusks or teeth live in the ocean buried. Open on both ends feed on animals in the sediment.

Mollusca Classification 

Gastropoda (snails)

Torison

evolutionary development in larvae

the development of the mantle cavity curves and ends on top of the animals head and gills where waste is dumped

Why? This creates a space that allows the animal to pull its head  back into its shell

Mollusca Classification

Gastropoda (snails)

One Gill

The having one gill works with the torsion problem because there is no longer a gill on the side of the animal that the anus is on so the water runs one way through the gill then to the anus and then out to the animal. There isn't any waste dumped into the gills anymore because that one is missing.

tropical marine snail and can extend part of its mantle out to sense prey and has a harpoon (radula) that it can fire at prey to inject conotoxin causes paralysis.

Mollusca Classification

Gastropoda (Snails)

Slugs, sea slugs, nudibranch

Pteropods-”sea angels” can flap their appendages to swim in the water and are very small: have very thin shell and are very sensitive to ocean acidification. If these die we could lose a lot of other species 

• clams
• oysters
• mussels

Oysters in the chesapeake: the chesapeake bay gets too much nutrients and sediment that makes the water dark. Plants require light to grow on the bottom of the ocean to create oxygen for the animals. 40% of the chesapeake is a “dead zone” because it has zero oxygen. 

The water is also dark because oysters don’t live there anymore. All bi-valves are filter feeders that eat bacteria and algae. So the water comes in through the gills (incurrent sipha) and then comes back out (excurrent sipha). When oysters filter feed they also bring in sediment because it is the same size as bacteria and algae. They cant filter nutrients which causes lots of algae and bacteria that use up all the oxygen creating dead zones. 

Two diseases swept through the chesapeake bay: dermo and msx: eukaryotic parasites of oysters (kill oysters) diseases the kill oysters require salty water

Oysters are keystone species: if removed the ecosystem undergoes a dramatic change

pelagic predators with evolutionary development of a loss of shell to allow for movement

as movement and size increases there is an increase in sense organs and size of brain.

communicate by changing colors

Mollusca Classification

Cephalopoda

Nautilus

Chambered Nautilus- can inflate back chambers with gas (oxygen) to get off the ocean bottom.

Arthropoda

General Characteristics

• coelomate animals
• protosomes
• 3/4 of worlds species
• bilaterally symmetry

Arthropoda Anatomy

Segmentation

body comes in repeating units

Tagmata: fusing segments into functional units

skeleton on the outside of the animal (also called cuticle) used for protection 

this is why arthropods are believed to be so successful

3 parts:

1. outer- epicuticle
2. middle- exocuticle
3. inner- endocuticle

fundamental unit of exoskeleton made up of a long chain of repeating sugars

Marine arthropods also use calcium carbonate in their skeleton

in order to grow the animal must malt, shed, or ecdysis

the land organisms have to be small in order to support skeleton

Arthropoda Anatomy

Muscles

striated muscle: striped, voluntary muscle

smooth muscle: not striped, involuntary muscle

Arthropoda Anatomy

Reduced Coelom

Arthropoda Anatomy

Complex Mouthparts

Arthropoda Anatomy

Open Circulatory System

blood is not contained in vessels

it washes through the body and holes in the heart

Arthropoda Anatomy

Respiration

Book Lungs: spiders consist of many parallel air pockets extending into a blood-filled chamber.

Tracheae: systems of air tubes that carry air directly to tissues from openings called spiracles.

Gills: we all know what gills are by now

Arthropoda Anatomy

Excretion

antennal, coxal glands

Spiders and insects: primitive kidneys

malphigian tubes: produce urine

crustaceans:(green glands) excretory organs produce urine

Arthropoda Anatomy

Nervous System

have a small brain

ventral ganglia:segments of clusters of nerves that function as cooperating brains.

decentralized: you can remove the brain and the organism will continue functioning

Arthropoda 

Subphylums

• Trilobita (no longer exsist)
• Chelicerata
• Crustacea
• Uniramia

Arthropoda 

Chelicerata Classes

• Merostomata (horseshoe crabs)
• Pycnogonida (sea spiders)
• Arachnida (8 legs)
  • order: araneae -spiders
  • order: scorpionida-scorpions
  • order: opiliones -daddy long legs
  • order: acari- mites and ticks

Arthropoda 

Crustacea Classes

• Branchiopoda: brine shrimp,sea monkeys, water fleas
• Maxillopoda: copopods, barnacles
• Malacostraca
  • Order: Euphansiacea-krill
  • Order: decapoda-crabs, lobsters,shrimps,crayfish

Arthropoda 

Uniramia Classes (10 legs)

• Chilopoda- centipedes
• Diplopoda- millipedes
• Insecta-insects

Arthropoda Crustacea Decapoda

Lobster Lifecycle

• larvae (pelagic) go through stages and swim to search for suitable habitat
• feed at night-need shelter and protection during the day
• grow to adult form
• males establish mating shelter big enough for two and blows chemical odors (urine released forward through jets in eyes) to attract female
• females then mate and malt at the same time using the male for protection while shell is soft during malting
• Internal  Fertilization: male inserts a spermatophore (packet of sperm). Female can hold sperm in seminal vessicle for up to a year

Arthropoda Crustacea Decapoda

Crab Lifecycle

• sponge crab: a female carrying eggs
• larvae hatch in ocean and move into bay
  • 1st larvae stage: zoea
  • 2nd larvae stage: megalopa
• Megalopa move into "first crab" stage and malt and grow rapidly while young and moving up the bay
• in one year they are adult size and are not tied to a shelter like lobsters
• sex is determined by apron shape
• females mate once in their lifetimes when they malt from immature to mature
• male picks of female and carrys her on his belly
• mating takes 10 hours and male give her all the sperm he has which is enough to lay eggs for the rest of her life
• female then moves down to the mouth of the bay never leaves

Arthropoda Chelicerata Merostomata

Horseshoe Crabs

anatomy

• chelicera: teeth
• Pedipalps: pinchers 
  • male: thick for latching onto females
  • females: thin
• gill flaps (operculum) means cover which protect respiratory flaps of the book gills

live on the atlantic coast and are most common in Delaware Bay and there is also a lot in the Chesapeake Bay

In the spring the females will develop eggs and move in shore (close to a beach). At night on a full or new moon in June (because of tide) the female will come up on the beach and lay eggs. The eggs require dryness of the beach (2 weeks which is the next high tide). Males will wait in the shallows looking for females and they will latch on to the back of her and be dragged up on the beach with her. As the female excretes the eggs the male excretes sperm and fertilizes the egg. Sometimes a female will have more then one male on her at a time.

Arthropoda Chelicerata Merostomata

Horseshoe Crabs 

The horseshoe crabs are used by people for bait so the population of horseshoe crabs is declining therefore the bird population is declining.

The are also important for human health. They have a unique immunity, in their blood they have amebocytes that attack bacteria in their blood and clot the blood. To test whether or not human blood is clean and free of contamination a group of scientists at the Marine Biological Labs developed a serum called Limuls Amebocyte Lysate. The serum would cause the clotting in the human blood if it had bacteria. It also changes color now to determine contamination.

Arthropoda Uniramia Insecta

General Characteristics

very abundant

primarily terrestrial: no marine some fresh water

their exoskeleton/cuticle prevents water loss

• complex mouth parts: labrum,manibles,maxillae,labium,hypopharynx
• Sense organs: antennae,
  • compound eyes: are really good at detecting motion. Not good for resolution and can’t form a stable image. Eyes are made up of units each unit or ommatidium functions seperately

Three Segments:

1. Prothorax
2. Mesothorax
3. Metathorax

walking legs on each section

usually two pairs of wings on meso and meta thorax

different insects have different arrangement for flight

slower-combination of: direct muscles are directly connected to the wing (flapping wing down)

indirect muscles are not directly connected to the wing ( attached at top of exoskeleton pull down make wings pop back up)

faster-have only indirect muscles that run from top to bottom (latitudinal) and also have muscles the run from front to back (longitudinal). The contraction of the longitudinal muscle contorts the exoskeleton to bring the wings down. One contraction gives you multiples beats of a wing which is called asynchronous intervation.

tracheal respiratory system

openings= spiracles

Arthropoda Uniramia Insecta

Metamorphosis

1. Complete (butterflies) holometabolous
   1. egg,larva,pupa,adult
   2. no competition between larva in adult since larva is completely different from adult
2. Incomplete (beetles, crickets) hemimetabolous
   1. egg,nymph,adult
   2. juveniles look like the adults
3. Hormones
   1. The Hormone that induces molting is ecdysone and is produced in a gland called the prothoracic gland (insects) Y-organ (crustaceans)
   2. The hormone that stops molting is called juvenile hormone or molt inhibiting hormone and is produced in the organ coropora allata (insects) x-organ (crustacean)

1. Visual (fireflies and femme fatales)
2. Chemical (Ants and Honey bees)
   1. ants leave odor trails
   2. honeybees leave chemical and visual signals (waggle dance)

Echinodermata

General Characteristics

• starfish,sand dollars,sea cucumbers,sea urchins
• dueterostomes
• all marine
• radial (pentaradial) animals

Echinodermata Anatomy

Endoskeleton

• ossicles: interlocking plates with tissue on the outside. Have spine that emerge from epidermis
• pedicellaria: small pinchers that are around the spine main function is to keep the animal clean

Echinodermata Anatomy

Feeding

eversion of the stomach 

the lower stomach or cardiac stomach come out mouth

Echinodermata Anatomy

Reproduction

• Dioccious
• Autonomy
• Regeneration
• Metamorphosis
  • Larvae are bilateral so they can move around then when metamorphosis occurs the larvae lays down on its left side and changes form and digestive tract.

Echinodermata Anatomy

Water Vascular System

• used for locomotion and feeding 
• is a series of hydrolic tubes that use water pressure to move
• Madreporite: on outside of the animal that fills and vents extra water in and out of system
• The System

1. Madreporite
2. stone canal
3. ring canal (central disc)
4. polian vesicles
5. lateral canal
6. radial canal 
7. ampulla
8. Tube foot: like a suction cup that is reusable via water moved in and out used for movement and feeding

1. Pelamtozoa
   1. Class: Crindoidea-old fashioned (sea lilies) have pinnules
2. Eleutherozoa
   1. Class: Asteroidea- sea stars, sea daisies
   2. Class Ophiuroidea- brittle stars, basket star
   3. Class: Echinoidea- sea urchins.sea biscuits, sand dollars
      1. irregular: elongated
      2. regular: rounded
   4. Class: Holothuroidea- sea cucumbers

      1. evisceration- if handled to roughly all their guts come out of the anus and then regenerates its internal organs