Invertebrates II Bio 1108

Mollusca

This phylum falls under the superphylum Lophotrochozoa

• Over 100,000 species

• predominantly marine

• consists of a mantle, muscular foot, and visceral mass

• has a complete digestive system

• Gills for respiration

• Open circulatory system (except for cephalopods who have a closed circulatory system)

• Radula

mantle

a fleshy dorsal body wall that secretes the shell and encloses the mantle cavity, which houses gills, anus, and other organs, and plays a role in respiration, excretion, and locomotion

Metanephridia

a type of excretory gland found in many types of invertebrates such as annelids, arthropods and mollusca

radula

unique tongue-like organ

Classes of Phylum Mollusca

• Class Polyplacophora

• Class Gastropoda

• Class Bivalvia

• Class Cephalopoda

Chiton

• Part of Phylum Mollusca

  • Class Polyplacophora

    • Many plates

    • Have radula to scrape algae off of rocks

Gastropods

Phylum Mollusca

• Class Gastropoda

  • Consist of snails, slugs (no shell), conchs, and nudibrachs

Bivalves

Phylum Mollusca

• Class bivalvia

  • Clams, oysters, and scallops

Cephalopods

Phylum Mollusca

• Class Cephalopoda (lit. head-foot)

  • Most unique group of molluscs

  • Closed circulatory systems

  • “Intelligent” group of invertebrates

    • Ex. nautilus, giant cuttlefish, reef squid, blue-ring octopus

Annelida

This phylum is characterized by rings that are distinct segments separated by a septum

Advantages of segmentation

Repitition provides backup

Coelom acts as hydrostatic skeleton

Permits specialization

Earthworm

Phylum Annelida

• Most advanced worms

• Double transport system

  • Circulatory system and coelomic fluid both carry nutrients, wastes and respiratory gases

• Complete digestive system

• Closed circulatory system

Classes of Annelida

• Class Oligiochaeta - Earthworm

• Class Hirudinea - Leech

• Class Polychaeta - Marine worm

Superphylum Ecdysozoa

This is a superphylum

• contains huge group of animals

• Includes Arthropods and Nematodes

• Ecdysis: external covering called cuticle that molts

• Separation from Lophotrochozoa supported by both molecular data and morphology

• Posses cuticle for support and protection

• Some have metamorphosis

Nematoda

This phylum consists of:

• Pseudocoelomates

• Many are parasitic with complex life cycles (such as heartwrom)

Tardigrada

This phylum contains organism that is an extremophile organism

Extremophile organism.
• Temperature range: -272°C to 150°C.
• Pressure: vacuum to 6000 atm.
• Can survive extreme ionizing radiation (UV,
X-ray). LD50 6,200 Gy vs 2.5 Gy human
• Can survive in water or survive desiccation to
1% water or less.
• Oviparous reproduction (lay eggs).

Arthropoda

• “Most succesful” phylum

• Over 1.1 million described living species

• Success related to body plan that permits them to live in all major biomes

• Exoskeleton made of chitin and protein

  • Can be extremely though or soft and flexible

  • Relatively impermeable to water

Arthropoda

This phylum consists of organisms that are:

• Key pollinators, decomposers, and crucial web participants

• Consist of segmented bodies that facilitate feeding and movement

• Can molt

• High reproductive rates

• Undergo metamorphosis

• Advanced sensory apparatus for communicating, matting, foraging, and predator evasion

• Small in size

• Short life cycles allow for rapid evolutionary responses

tagmata

fused body segments/distinct body segments

chitin

material that makes up exoskeleton of arthropods

open

Arthropods have this circulatory system

hemocoel

cavity containing organs

gills or trachea

two ways in which arthropoda respirate/conduct gas exchange

Subphylums of Arthropoda

• Subphylum Chelicerata

• Subphylum Myriapoda

• Subphylum Crustacea

• Subphylum Hexapoda

Chelicerata

This subphylum contains spiders, horseshoe crabs, ticks, and scorpions

Myriapoda

This subphylum contains centipedes and milipedes

Crustacea

This subphylum contains crabs, lobsters, and crayfish

Hexapoda

This subphylum contains beetles, flies, butterflies, and fleas

Chelicerae

claw-like or fang-like mouth parts

Chilopods

Aka centipedes, contain one set of legs per segment and are carnivores

Diplopoda

Aka millipedes, contain two sets of legs per segment, and are herbivores

carapace

the hard upper shell of a crustacean

spiracles

respiratory openings, found in insects and some fish, that allow air or water to enter their respiratory systems

Echinodermata

This phylum breaks down to mean spiny skin

• adults exhibit pentaradial symmetry

• Larval forms have bilateral symmetry

• Capable of regeneration

• Water vascular system

• No head region

• Have a nerve ring

• Contains organisms such as sea stars, brittle stars, sea urchins, sea lilies, sea cucumbers

water vascular system

network of hydraulic canals unique to echinoderms, like starfish and sea urchins

• facilitates locomotion, feeding, and respiration through controlled water movement

madreporite

a perforated plate by which the entry of seawater into the vascular system of an echinoderm is controlled

Subphylums of Chordata

• Subphylum Cephalochordate

• Subphylum Urochordata

• Subphylum Vertebrata

notochord, dorsal hollow nerve cord, pharyngeal gill slits, and post-anal tail

fundamental chordate characteristics

Cephalochordate

Invertebrate chordates - lancelets

Small filter feeders that bury in substrate

Urochordata

Invertebrates chordates - tunicates

notochord

flexible, rod-shaped structure that runs along nerve chord

• in vetebrates, it develops into the vertebrae

dorsal hollow nerve cord

develops into spinal cord in vertebrates

pharyngeal gill slits

• in vertebrate fish - these develop into gill support

• in tetrapods; develop into parts of ears and tonsils