Higher Order Invertabrates
• Mollusks- One of the largest and most successful group of animals. The range in size from microscopic snails to the giant squid. Some mollusks, such as oysters, scallops and conchs are food animals for human whereas others, such as shipworm cause commercial damage.
The generalized molluscan body plan consists of two major parts: The head-foot and the visceral mass. The head foot region contains of the head, with its mouth and sensory organs, and the foot. The dorsal visceral mass contains the other organs systems including the circulatory, the digestive and the respiratory.
• Arthropods- Animals with joined appendages.
• Represent the most successful group of animals in the animal kingdom.
• Almost 75% of all identified animal species belong to phylum.
• There are two major groups of marine Arthropods: Chelicerates and Mandibulates.
• They are also bottom feeders.
• Chelicerates include ticks, scorpions, horseshoe crabs, and sea spiders.
• Mandibulates have mandibles on their head that are modified for feeding.
Echinoderms-
• Represented by well-known animals such as sea stars, sea urchins, and sea cucumbers.
• Their name refers to the spiny skin that these organisms have
• Echinoderms are benthic creatures that can be found at all depths. Sea cucumbers and brittle stars are common deep sea organisms.
• Echinoderms have spiny skin because of their endoskeleton that lies beneath the epidermis.
• The Endoskeleton is made of calcium carbonate plates.
• Echinoderms have tiny sharp structures around the base of the spine called pedicellariae.
Tunicates
-Mostly sessile (immobile) animals that are widely distributed in all seas
-Named after their body covering-which looks like a tunic
-They are Hermaphroditic, meaning they all contain both the male and female reproductive organs
Sea Squirts:
-Get their name from their temper- they forcefully expel a stream of water from their excurrent siphon
-The two tubes projecting from them are called:
•Excurrent Siphon: gets rid of water and waste
•Incurrent Siphon: brings in water and food
-Can regenerate body parts
Salps:
-Free-swimming tunicates with their incurrent and excurrent siphons located on opposite ends of their barrel-shaped bodies
-Some species are bioluminescent
Larvaceans:
-another group of free-swimming tunicates
-produce delicate enclosures made of mucus used in feeding
Cephalochordates:
-Fish-like chordates that are collectively known as lacelets
-Eat plankton and diatoms
-Produce by releasing their egg and sperm into the water
-Live in shallow temperate and tropical regions
Lancelets:
-Slender, laterally compressed, and eel-like in appearance and behavior
Bivalves:
-Soft bodies covered by hard shells made of calcium carbonate
-Body plan consists of two parts: head foot (tongue) and the visceral mass (everything else)
-Shell has 3 layers: outermost, middles, innermost
-Cephalopods have an ability to squirt, fishermen call them inkfish
-Cephalopods also have bilateral body symmetry, a prominent head, and a set of arms or tentacles
- 800 extant species of cephalopods exist today
-found in ALL oceans of Earth