chapter 30

Diversity of Invertebrates IV Lecture 30 (Chapter 33)

Variable Bushy Feather Star

  • Scientific Name: Comaster schlegelii
  • Location: Kosrae, Micronesia
  • Date: 24 June 2013

Biblical Reference

  • Quote: "How many are your works, Lord! In wisdom you made them all; the earth is full of your creatures."
  • Source: Psalm 104:24 NIV
  • Location: St. John, US Virgin Islands
  • Date: 9 June 2003

Bryozoans (Phylum Bryozoa)

Characteristics
  • Symmetry: Bilateral
  • Size: Tiny
  • Habit: Most are sessile
  • Colony Type: Most are colonial
  • Habitat: Marine and freshwater
Example Species
  • Kelp Lace Bryozoan
    • Scientific Name: Membranipora membranacea
    • Location: On Bull Kelp (Nereocystis luetkeana)
    • Date: Salmon Creek, California, 25 October 2022

Lophophore

Definition
  • A ciliated, tentacular structure used for filter feeding.
Example Species
  • Keyhole Bryozoan
    • Scientific Name: Cryptosula pallasiana
    • Location: Berkeley, California, 5 January 2025
  • Leather Bryozoan
    • Scientific Name: Flustrellidra corniculate
    • Location: Goat Rock Beach, California, 12 September 2021

Lamp Shells (Phylum Brachiopoda)

Characteristics
  • Symmetry: Bilateral
  • Resemblance: Resemble bivalve mollusks, but the ventral valve is usually larger.
  • Lophophore: Have a lophophore
  • Habit: Sessile
  • Habitat: Marine
Historical Context
  • Abundance: Lamp shells were abundant during the early Paleozoic era.
  • Extinction: Most species are now extinct.
Graph - Decline of Brachiopod Bivalves and Rise of Mollusk Bivalves
  • X-Axis: Millions of years before/after the end of the Paleozoic
  • Y-Axis: Number of genera
    • Brachiopods: 400
    • Bivalves: Increasing trend from near extinction of brachiopods.

Echinoderms (Phylum Echinodermata)

General Characteristics
  • Common Name: “Spiny skins”
  • Examples: Sea stars, brittle stars, sea urchins, sea cucumbers, crinoids
  • Body Symmetry: Radial or bilateral
  • Body Structure: Body parts usually pentamerous (multiples of 5)
  • Skeletal Structure: Internal skeleton composed of calcium carbonate (CaCO3) ossicles
  • Habitat: Exclusively marine
  • Environment: Benthic
  • Mobility: Most are motile
Specific Examples with Locations and Dates
  • Red Cushion Sea Star (Oreaster reticulatus):
    • St. Thomas, US Virgin Islands, 5 May 2003
  • Pingwe, Tanzania: 18 July 2023
  • St. Thomas, US Virgin Islands: 27 April 2003
  • Kosrae, Micronesia: 19 June/25 June 2013
Sea Stars (Class Asteroidea)
  • Structure: Star-shaped, with arms projecting from a central disc.
  • Arm Characteristics: Arms usually wide at base and narrow at tip.
  • Coelom: Extends into arms.
Important Anatomical Features
  • Ambulacral Groove
    • Definition: Groove along the oral surface of each arm
  • Podia
    • Definition: 2-4 rows of tube feet in the ambulacral groove.
  • Pedicillaria
    • Definition: External projections of internal skeletal ossicles.
  • Madreporite
    • Definition: An intake pore for the water vascular system.
Anatomy of Sea Stars
  • Components include:
    • Mouth
    • Anus
    • Ambulacral groove
    • Tube feet
    • Madreporite
    • Arms
Feeding Habits
  • Diet: Most are carnivores; primarily preying on bivalves.

Brittle Stars (Class Ophiuroidea)

Characteristics
  • Arm Structure: Arms narrow, solid, and lacking an ambulacral groove as well as coelom.
  • Branching of Arms: Arms branch into a bush-like structure in basket stars.
  • Podia Function: Podia are not used for locomotion; most are scavengers or detritivores.
Examples
  • Flat-spined Brittle Star (Ophiopteris papillosa):
    • Location: Mendocino Headlands, California, 15 May 2021
  • Long-armed Brittle Star (Amphiodia occidentalis):
    • Location: Bolling Ball Beach, California, 12 September 2020

Sea Urchins (Class Echinoidea)

Characteristics
  • Body Shape: Spherical or oval shape.
  • Spine Movement: Spines move in ball-and-socket joints.
  • Plate Structure: Five alternating plates with podia; pairs of holes on plates.
Notable Features
  • Aristotle's Lantern
    • Definition: A 5-sided feeding structure in sea urchins, consisting of 5 retractable teeth.
  • Diet: Most are herbivores or scavengers and many burrow into rocks.
Example Species
  • Pacific Purple Sea Urchin (Strongylocentrotus purpuratus): Mendocino, California, 30 June 2021
  • Eccentric Sand Dollar (Dendraster excentricus): Monterey, California, 6 September 2020
  • Savigny's Longspine Sea Urchin (Diadema savignyi): Pingwe, Zanzibar, Tanzania, 18 July 2023

Sea Cucumbers (Class Holothuroidea)

Characteristics
  • Body Structure: Body is long and usually cylindrical.
  • Podia Structure: Five rows of podia; three ventral rows used for locomotion.
  • Mouth Location: Mouth at anterior end, surrounded by tentacles.
  • Feeding Habit: Most are detritivores.
Example Species
  • Leopard Sea Cucumber (Bohadschia argus): Kosrae, Micronesia, 19 June 2013
  • Graeffe's Sea Cucumber (Pearsonothuria graeffei): Kosrae, Micronesia, 19 June 2013
  • Snake Sea Cucumber (Synapta maculata): Kosrae, Micronesia, 19 June 2013
  • Warty Sea Cucumber (Parastichopus parvimensis): Santa Cruz Island, California, 18 June 2016
  • Orange Sea Cucumber (Cucumaria miniata): Mendocino Headlands, California, 15 May 2021

Crinoids (Class Crinoidea)

Characteristics
  • Arm Structure: Arms usually branch after leaving the central disc.
  • Pinnules: Each arm has two rows of jointed pinnules.
  • Feeding Habit: Filter feeders.
Examples
  • Variable Bushy Feather Star (Comaster schlegelii): Kosrae, Micronesia, 25 June 2013
  • Bennett's Bushy Feather Star (Anneissia bennetti): Mana Island, Fiji, 20 July 2019
Cirri
  • Definition: Curled, finger-like appendages for attachment at the bottom.

Acorn Worms (Phylum Hemichordata)

Characteristics
  • Symmetry: Bilateral
  • Body Structure: Worm-like with 3 body parts: proboscis, collar, trunk.
  • Habit: Most are solitary, benthic, and deposit feeders, living in burrows.
Example Species
  • Acorn Worm (Saccoglossus pusillus): San Francisco Bay, California, 28 October 2021

Chordates (Phylum Chordata)

General Characteristics
  • Notochord: A cartilaginous skeletal rod supporting the body, occurs in all embryos and some adults.
  • Dorsal Nerve Cord: A hollow, fluid-filled tube of nervous tissue above the notochord.
  • Pharyngeal Slits: Temporary openings that develop in the pharynx (throat) of embryos.
  • Post-anal Tail: Present in embryonic, larval, or adult stage.
Anatomy Overview
  • Components Include:
    • Incurrent siphon
    • Sensory structure with eye
    • Excurrent siphon
    • Anus
    • Dorsal nerve cord
    • Notochord
    • Post-anal tail
    • Stomach
    • Pharyngeal slits
    • Heart
Subphylum Tunicates (Urochordata)
  • Body Shape: Spherical to cylindrical.
  • Siphons: Incurrent and excurrent siphons.
  • Larvae Features: Larvae resemble other chordates with a tail containing a notochord and dorsal hollow nerve cord, which disappear in adults.
Examples
  • Giant Tunicate (Polycarpa spongiabilis): Mana Island, Fiji, 23 March 2023
  • Green Barrel Sea Squirt (Didemnum molle): Pingwe, Zanzibar, Tanzania, 18 July 2023
  • Unidentified Tunicates: Various locations in San Francisco Bay and Mendocino Headlands.
Lancelets (Subphylum Cephalochordata)
  • Characteristics: Small, fish-like; filter feed with pharyngeal gills.
  • Habitat: Most found in shallow coastal waters.
Example Species
  • European Lancelet (Branchiostoma lanceolatum)
  • Unidentified lancelet: Found in central California.
Vertebrates (Subphylum Vertebrata)
  • Discussion: To be covered in the next lecture.
  • Example: Maasai Giraffe (Giraffa tippelskirchi) from Maasai Mara National Reserve, Kenya, 27 March 2022.

Quiz Preparation

  • Study Focus: Review for a quiz over lectures 29-30 (Chapter 33).