Porifera: Sponges - Biology PDF
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This document provides an overview of the characteristics, anatomy, life functions, and significance of Porifera, commonly known as sponges. It covers general features, key definitions of relevant terms like ectoderm, endoderm, and mesoglea. The document delves into the anatomy and structure of sponges, highlighting their lack of tissues and organs, and emphasizing their unique cellular composition. It also examines their life functions, reproduction mechanisms, and broader significance to marine ecosystems.
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General Features: - Pore-bearers - Primitive and ancient - all are aquatic - thought to be plants but no cell walls and are multicellular eukaryotes, and heterotrophic - some live in freshwater and streams, most are marine - adults are sessile (attached to either rock or seaflo...
General Features: - Pore-bearers - Primitive and ancient - all are aquatic - thought to be plants but no cell walls and are multicellular eukaryotes, and heterotrophic - some live in freshwater and streams, most are marine - adults are sessile (attached to either rock or seafloor) - found on rocks, docks, and pilings (deep underwater) Key definitions:\ **Ectoderm** = outer layer, flat cells\ **Endoderm** = inner layer, collar cells\ **Mesoglea** = jelly layer Anatomy/Structure: - Lacks tissues and organs, but consists of a bunch of specialized cells that live and work together - most grow upright in a tube or branch form - have big holes at the top, called **oscula** (p) or **osculum** (s) - some sponges grow in thin layers to coat surfaces aka encrusting sponges - others can bore into hard surfaces (ex. coral, rocks, shellfish) - water enters through spores and out through osculum - have 2 cell layers with a jelly like layer in between (ectoderm, endoderm, and mesoglea) - Collar cells, aka **choanocytes** have flagella that create water currents - **Amoebocytes** are in the mesoglea, and make small branches/spines (aka **spicules**) which form support framework for sponges - Spicules can be made of silica glass, calcium carbonate chalk, or spongin soft protein Life Functions: - all life functions occur through water currents (current brings food and O2 in, carries out garbage) - Filter feeders, food gets trapped by collar cells and engulfed by endocytosis - Amoebocytes transport food to other cells Overall Significance: - Provides habitats and food for many organisms - Has symbiotic and commensal relationships with many marine invertebrates - food for some organisms - ex. Sea turtles, sea stars, and fish - Historically dead sponges used for bathing - chemical made by sponges to prevent algae and bacteria from growing on them is also used industrially - produces antibiotics and is drug effective against leukemia, arthritis, and strep throat Reproduction: - Some sponges have no gender, sexual amoebocytes → gametes (just gametes egg and sperm) - Gametes get released into water and leave through the osculum - After fertilizing, the flagellate swims around until it's divided and too heavy to swim, drops into the ocean, attaches to substrate and grows (only motile state of sponges) - asexual gemmules form when conditions are bad (freezing, drought) - capsules of spicules wrapped around amoebocytes - can also reproduce by budding or fragmentation
